Most pet store empolyees are not experts. In fact, a lot of them know nothing at all, or know faulty information. This isn't to say that they are all ignorant, lol, but some are worse than others..
I wouldn't handle for the first week or so at all to keep stress down and help it acclimate without bothering it and scaring the little thing. If you already have handled it, you can't exactly 'take it back', but that doesn't mean you should continue, wait a few more days. 3-5 mins won't kill it but let him settle in
I am exhausted so sorry if that didn't really make sense