When the water is preheated, naturally the temp drops from putting food in. However then the app doesn’t start the timer until it is back 1 or 2 degrees. Should I just use another time and count the time with food in, just a few degrees shy? Or should I wait till it is completely preheated and go with the app timer?
I wouldn’t worry about it and just let the timer start when it comes back up to temp. I can only think of a very few things that you could cook sous vide that would be affected by a difference in cooking time of a mere couple minutes.
I just drop the food in during the preheat and then I don’t have to touch it.
A few things like eggs are time critical. Everything else cooking for a few extra minutes no real impact. I typically add my food sometime during the preheat and by experience I know how long it will take to reach the proper cooking temperature. I also start out with hot tap water to reduce the time.