This is going to vary by 400% or more depending on the company you choose to build your pool and the requirements of any HOAs or municipalities that will be involved, weather, access and the size and complexity of the project.
Let me start by saying that construction a swimming pool on your property is not process you want to rush. That being said, a fairly simple pool or pool spa, in perfect conditions, can be completed in about 3 months. Although we at Accredited Pools Inc. have accomplished in era of Covid, For simi basic pool projects we tell our clients to expect about 4 ½ months as many things, mostly weather, effect completion times. The high-volume pool companies in our area are taking 17 months from signing to completion. Too many unsuspecting homeowners pay a large deposit to companies or individuals come dig a hole then never come back seriously effecting completion times. We completed 3 pools for customers last year that were started and abandoned by the pool contractor and contacted by several others with this situation. By the time the homeowners exhausted all attempts to get the project completed and accepted that it was not going to happen and get someone to complete it, the project took well over a year  

ACCESS AND WEATHER
Much of the time, the access to the pool location is across the grass and along the side of the house. If the access space is narrow smaller equipment will be needed to dig and remove the spoils adding to the construction time. When you add rain to the mix, the saturated ground will create a big mess causing property damage if you try to run heavy equipment, trucks, trailers, etc. back and forth in these conditions. It may take 3 or 4 days for the ground to dry out enough to continue work so if it rains every 3 or 4 days it can really lengthen the overall construction time.

SCOPE OF WORK
It is not a good idea to plaster a pool before other work like patios. pergolas casitas and especially landscaping as dust and other elements from the process of completing them can permanently stain the pool plaster and totally mess up the water chemistry. We have many projects that include outdoor kitchens, extensive decking and retaining walls, fireplaces, and landscaping. We will dig and construct the pool shell, do the tile and coping and any concrete work, then complete all other work including landscaping. Only then will we plaster the pool, fill it with water and start it up.
Depending on the complexity of the other amenities included in the project, the completion times are extended accordingly

Permits inspections
If your pool requires permits, inspections and or HOA approval, construction times are extended in proportion to the efficiently of the municipality. One of our local municipalities the City of Lakeway takes much more time and effort to obtain the permits than to actually build the pool.
Availability of materials
In recent times the availability of various materials and equipment have been problematic extending completion times and disrupting schedules. Hopefully we will see less of this in the future with covid related issues decreasing.

How much does a pool cost?
Well, that’s a lot like asking how much does a car cost.
There are a lot of variables. Is it a Ford focus or a Range Rover Defender?
All pools are not created equal.

A swimming pool can be the ultimate pleasure to add to your life, or it can be a hole in the ground that you throw money into with constant regret.

There are many things a pool builder can do to save a lot of money building your pool.
Most of them are a very bad idea. The cost of correcting mistakes on a swimming pool can be equal to or more than the cost of the pool.

Parts like the valves that you turn to adjust the various pool water functions can be purchased at Home Depot for $8-12. Those will last a few years and cost several hundred dollars to replace and are a lot of hassle to use. Or you start with high quality valves, costing $60-$150, which are trouble free and are serviceable for a lifetime. With 3-6 or more of those valves on your system, you can save some money upfront by going cheap, but you will be left with a lifetime of headaches and future expenses to replace them. 

The pricing on the pumps above is a great example of the cost differences between product choices. Imagine the savings to a builder using the Home Depot product when your pool requires 2 or 3 pumps. A builder can save a lot of money by using inferior products. With a difference in pricing of more than tenfold on many of the products that make up a swimming pool, you really need to be well informed on which products your pool builder will be using on your pool. Does more expensive always equal better? No! Some products are more expensive like Jandy stealth pumps, for example, which we have found don’t last and are a constant ongoing expense.

With the cost of concrete these days, the size of the pool deck will affect the cost of the pool dramatically. Currently in our local area, the price for high quality concrete work is about $28 a square foot so if you have no decking vs 1,000 ft of decking, that is a huge difference in the total price of the pool. Swimming pool decking (the concrete around your pool) is highly specialized. The method to do it correctly, with the proper details specific to swimming pool, is not the same as the foundation of a sidewalk. It is more complex and just more expensive to do it correctly.

Quality workers and sub contractors cost a lot more than those of lower quality. What is the condition of the soil? Solid rock? Expansive clay? Just imagine using the lowest cost pool builder to build a pool in bad soil. Bad things are going to happen.

How about the plaster?  Plasters are made from a wide variety of materials, from very soft marble dust to very hard granite and quartz, with the lifespan, cost, and beauty varying accordingly. 

Because owning a pool that is inadequate in some way is usually costly and stressful, the question you actually want to ask is, “What is the cost to build a good quality swimming pool from a reputable, experienced pool company that is financially able to complete your project, that will be around and profitable enough to take care of any warranty issues that come up in the future?"

In the Austin area, a quality pool is going to cost starting around $85k and a pool/spa combo will start at $95k. Typically home owners are opting for a total backyard makeover with outdoor kitchens or pergolas, which will cost $150k-$250k. Paying this much for a pool and all the goodies does not automatically mean you will get the quality you should be getting at this price point. We see pools all the time that people have paid a lot of money for that were constructed with the lower cost components. So it's important to either be well informed about exactly what products and methods are going into your pool project, or work with a knowledgeable contractor with the experience and ethics  to build you a good pool.