Light and air if not evenly applied can quite rapidly alter the appearance of a number of bare woods. Cherry will "sunburn" within hours.
Now, if you wood has been stripped, there's some likelihood that the traces of remaining finish will negate the effect. You won't really know until you go to put the finish on. Maybe a water-based stain and finish would allow you to proceed now.
Casey

To add to Casey's advice, leaving sanded wood open to air for several months can allow dirt and debris to collect on the wood surfaces that can cause problems when finishing---fisheye as the major example.

If polyurethane is the finish, why wait? Use a waterborne urethane. General finishes has a really good one. My mom, an old grandma, finished all the millwork when they had new windows installed throughout their home. She achieved excellent results, with just sand paper and a paint brush.

General Enduro is the product line. The finishes are brushable, even the precatalyzed can be applied by brush, just mix in the crosslinker additive.

Thanks for the information!

To give some more background: The woodwork is chestnut and was originally shellac-ed. I finished several rooms of woodwork over the summer, with oil-based stain and polyurethane, so I want to be consistent.

I am staining the woodwork with a gel stain (to mask some of the imperfections in the old wood), so perhaps that will help with the effects of exposure to air and light? Would it work to leave the final round of sanding (with 120 grit) until later, or will I be sanding off too little to make any difference with regards to air/light exposure?

"The woodwork is chestnut and was originally shellac-ed. I finished several rooms of woodwork over the summer, with oil-based stain and polyurethane"

ouch.

Shellac is still available in many shades (types) and is a far better finish than poly.

The original shellac was buried under 5 or 6 layers of paint and mostly came off when the paint came off. I only mentioned it because there may be some residue.

I prefer inferior finishes so I'm glad I went with poly as a replacement :)

Don't take this the wrong way. I am not trying to be rude. If we were teaching and learning in person, I'm sure we would like each other. I respect your ambition, that alone makes you a worthy student. But please listen:

If you prefer inferior, you're definitely on the right track. Every one of us answered your initial question with a thoughtful, professional answer.

The answer was unanimously "YES THERE ARE PROBLEMS WITH LEAVING BARE WOOD EXPOSED FOR A LONG TIME!" Additionally, every answerer recommended not using oil based poly.

You seem to only want to hear reassurance that your way is a good way.

It is not a good way. You are just wasting time and possibly ruining some irreplacable antique woodwork. Chestnut is not easy to find these days.

If you are here to learn, please respect the teachers. We are volunteers. It is upsetting to volunteer time to someone who makes a joke about the effort. Joking about being glad to use an inferior finish is a bit like making fun of the lesson.

At any rate, best of luck.