ps, u r right, theres always a risk. the point is when u go for the stamping, fill up the ds156, it has a ques saying "have u or anyone on ur behalf ever filed an immigration petition?" so not just ur resume/h1b credentials are evaluated at the interview, that u hv applied for an imm visa becomes a eyebrow raise. w/o the notice of receipt, it becomes more nervous face and they see that on ur expressions.
shirtanswer, when u say, is it valid? its a valid/legal status, but NOT A VISA, till it is in ur PP. so no, thats not what i meant when i was asking ps about it. ps has a valid VISA ( not just 797), so he is cool.
my best bet would be, if all else (ur job/pay stubs, resume matching the job desc, emp letter etc etc) are fine, then wait till u actually get ur notice of receipt n then travel. it gives ur face a little more confidence while u r standin before the counsler. otherwise, legally speaking, u r fine even today, coz h1b, unlike f1 or b1/b2, is a dual intent visa. and they can not give u a 214. however, when in doubt, they give a 221g, which , my friend, is much worse, coz that means, suspended decision on visa app and awaiting backgroung check. i amsure we know how painful it may get if u are stuck outside with 221.
anyway, these are subjective viewpoints on objective facts, decision is yours.##good luck.
jai mata di!