Ian's right. Your test strips should reveal all. If you do worry about development times (perhaps because of the colder weather) it might be worthwhile to make a set of identical test strips put them in the tray together and pull them at 2 mins, 2.5 mins, 3 mins and so up, perhaps up to double your standard time, then wash and dry them and see if you could see any difference at all. The drying is important because any differences will be small. That would give a sound footing for a personal print development time. Some people do follow the book and some like to give a little more "just to be sure..." It's all decided by the results.