some first time lambers are a but difficult about letting the lamb(s) suckle, so I always watch them and if they back off as lamb tries to latch on, they are penned (usually I try and wait until lamb has found teat) and I hold the ewe and guide lamb. I wouldn't up-end the ewe so soon after birth, all her innards are loose and a bit out of place. after a few feeds mum is usually ok, although I had one last year that had to have the lambs brought to her and placed on for about a week... she was great mother after that though...
I wouldn't wait for more than an hour before putting the lamb onto the teat, but it depends a bit on the breed (are they up quickly or a bit slow in general) and also if it was slow (and difficult) or quick, easy birth. In preference I always milk the ewe, and only use the powdered colostrum if triplets or really the ewe doesn't have any. If another one is about to lamb (or has just lambed) milk her for some if she has plenty, even if only for the first feed.