It's best to soak at least once a week. I used to soak my russian tort three times a week. If the enclosure it lives in has a water dish, one soak a week will be fine. For five to ten minutes per soak is good.
If your tort is new and came from a pet store, I'd soak daily for 20 minutes for the first couple of weeks as they often are a little dehydrated and don't eat properly while deciding that their new home is safe.
Do the soak first thing in the morning before he's warmed up properly, feed straight after the soak and then walk away and leave him to be brave and explore.
I can't say I'm an expert on Russians but I read almost every post made daily on the forums the best I can and I've picked up little info here and there and soak up peoples advice like a sponge. Russians don't need high humidity, so I would say you are just fine with once or twice a week.
I soaked my Russians everyday when I first got them. After 2 weeks or so I stopped doing it daily.
Now, the only time they are soaked is every week or so in a tub while I garden in their outdoor pen. Mine live outside full time and get hosed daily when I water their plants. They also have unlimited access to water dishes and different micro climates.
Thanks everyone! I have had him since May 27th, but will start soaking him daily for a couple weeks. He really seemed to like it this morning However I do think it was a bit cool considering the feedback I have read here.
You can experiment with the soaking temperature to find the perfect temperature for relaxation. The water should be warm, not hot... To me "luke warm" means water that doesn't feel cold to the touch, but doesn't feel warm either... and that would be too chilly for Joe!