I am building a home (first time!) in a location about 2 1/2 hours from where I live. Can anyone provide me with critical checkpoints in the construction process where I should make an onsite visit?

molly there are stages in home building .site cleared check .foundation in first 2nd framed 3rd sheethed he plumbing heast so forth roofing siding all that ****

Personally, I would want to be on site any time an inspection was being performed, and would likely throw in several unscheduled "surprise" visits. The more involved you are in the process the happier you will be with the finished house and the fewer unpleasant surprises you will have down the road.

Watch a few episodes of Holmes on Homes on Discovery Home channel and you may want to camp out on site for the whole process!

I totaly agree with La Marlowe on this one.
Unless the person that is building this home is a long time friend or family member I would not trust anyone or anything they are doing.
Of course if your buying a home that is being built as part of a group of homes in a develpoment no matter when you come to visit they most likely not change anything anyway.

But if your stick building the house on your own lot and with your own plans and you hired the general contractor. Buy a tent and live there.
If its part of a development. If you can and I doubt you will be able to. You want to be there for
1. Foundatin water proofing phase. (before they back fill)

2. Framing (before they start cutting the house apart for plumbing, electrical and HVAC) I have been on sites where the owner once they saw the floor plan framed out ended up wanting walls moved or room layouts done diffrent. You do not want to change after the other trades have been there. Also you want to see where everything is being placed. i.e. Sinks, vents. Major appliances etc.

3. Siding process to be sure its the color and style your paying for.

4. Interior finish work. To be sure they are not painting or trimming wrong styles or colors.

5. Exterior landscaping.

However if you do not understand the process of building a home. You need someone with you that does. Otherwise you will not have any idea or what your looking at in most cases.

I had a past client who played professional football. His wife who lived in California at the time became the general contractor for their home in NJ. She hired a local contractor who was supposed to run the job and be her eyes and ears while she was out of town with her husband. Which was most of the time. It turns out the person he hired ended up sub-contracting his job because he was out of town himself.
To make a long story short. The house was a mess. Because she was the person who was supposed to be building the home and selecting contractors etc. She was responsible for everything everone did.
After she went after everyone in court that did work for her she ended up with mostly nothing in return. The moral of this story is:
If you want something done right. Do it yourself. Live in the area, Visit as much as you can. like every day. Otherwise the job will crawl to a stop evertime someone needs an answer to something.
Good luck. Its not an easy job. But great feelings will come to you when its done.