fresh rebuild start up problem

You should be okay, I know when I was firing mine for the first time it took a few revolutions to get it going, well it sputtered a few times and died. Mind you I had maybe only about 15-20 seconds of crank time with a few quick fires during that. I have about 600 miles on the motor now and my cam is perfectly healthy!

I hope you are using a good break in oil or additive? because from what I understand the lube you put on the cam is gone pretty quick, and once its gone its up to the additives in the oil to protect the cam. Also change the oil right after, you would be amazed what the oil looks like, mine looked pretty dirty, and I thought something was wrong. But after my third oil change at the 500 mile mark its starting to look pretty clean now, and I'm getting barely anything on my magnetic drain plug. Also it wouldn't hurt to open up the oil filter to see what it looks like.