Not to highjack but how big a problem is latent image degradation.
I've never noticed any by eye but have never done any tests.
As mentioned in the OP, I had been lazy developing rolls and storing them in a cupboard. About three years later (hey, kids will do that to you!) the tri-x, hp5+ and fp4+ came out OK, but there was significant degradation of panf+.
Thanks for all the helpful advice. Rather than putting them in the fridge, I will store my exposed film in a dry place in ziplocks from now on. Seems like Perceptol also has a longer shelf life than I had expected. I will develop Panf+ immediately after exposure.
This was of great help!
There is a thread here on APUG showing film speed reduction due to latent image degradation. The data shown tells me that you lose a lot in the first few hours but after that there is little difference between waiting one day or three weeks.
And you yourself might be in a good position to check actual shelf life of your developer: When you are about to finish some old stock, mix fresh stock and do a direct comparison with two identically exposed test clips. No mathematical equation and no lab reference data will be able to tell you as accurately as this simple test what happens if you store Perceptol for a few months in your environment.
Trying to be the best of whatever I am, even if what I am is no good.
How fast the latent image degrades depends on many things including the specific film (each film is different) and the storage temperature. From posts here on APUg it is hard to detect any changes for several weeks or months except as Rudeofus notes.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.
I can share my own personal experiences along these lines. I develop with D76 (also a powder, like the OP is using) and had similar concerns about leaving unused stock solution for months, so I stockpile my exposed films until i have enough to use up an entire batch of developer. After shooting a film I stick it in the freezer - in the original plastic canisters for 35mm or in tightly wrapped plastic bags for 120. Sometimes the films aren't developed for nearly a year. I understand that there may be risks with condensation or latent image degradation, but to my untrained eye I've never seen any ill effects whatsoever. I've used a mixture of Tri-X, Plus-X, T-Max 400, FP4+ and HP5+ and they've all been fine.