We have an in-ground pool with plaster that was finished about 2 months ago. Due to the new plaster, the pH is constantly creeping up and I have to add muriatic acid every couple of days to keep it down.

We're ready to winterize for the season now. Should I be doing any monitoring or adjusting of the pH over the winter, or is it ok to just leave it alone until summer?

Don't winterize now, wait until the water is below 50 degrees, preferably well below 50. You also need to open in the spring as early as possible. Colder water will slow down the curing process, which will reduce the rate of PH drift. Even so, it is still a good idea to check the PH occasionally through the winter if doing so is practical. Monitoring is most important when the plaster is applied in the fall. You have a couple of months already, so you will probably be alright as long as you wait until the water is as cold as possible before closing, but monitoring the PH is safer.

Thanks!

When I check pH occasionally through the winter how to I go about adding acid to correct it if needed? I assume that with the pump not running the water won't circulate and mix the acid properly, right?

Where are you located?
If the pool doesn't freeze then I'd drop a submersible pump in to circulate the water so when you add acid you could run the pump.

My pH drips up all year since last October build. In the winter, we had the pH at about 7.2 and left it alone all winter. it was a little high when we opened, but still in the 7.8-7.9 range. All year, it keeps drifting up since it's about a year old. I think you'll be fine all winter once it gets cold.