My policy is to leave them alone for four to five days, which is when I offer their first meal. Right or wrong, I don't change their water during this period. I think my arm reaching in and out is just adding to the stress. I'll fill it if it needs it, but otherwise I leave them totally alone other than peeking from a respectable distance (meaning I don't press my nose up to the glass
)
The first time, I handle for 10 or 15 minutes max. Which is basically enough time to snap a couple of pictures, including one to use to get a length measurement and weigh them.
My experience is limited to two from 01 and three from this year... so take it (my advice) for what you think it's worth