I agree, many of my females will soak for weeks at a time(if given large enough water bowl) right up to ovulation. BUT if she is in shed it may just because of that as many snakes like to soak when in shed.
If she is not in shed, is glowing and soaking for long periods, I would wait until she stops soaking and then check on her twice a day and watch for ovulation. I have caught many girls this way. I have taken pics soaking and then around 3 weeks later ovulating. I have one female soaking right now.