340 camshaft break-in. Well.....almost

Thank you!! Bet the fingers get tired doing that for 20 mins Haha. How long after the start do you have to hit 2000-2800 rpm? Do have have time to check the timing and make adjustments? Or is it as soon as it hits put the the throttle down and hit 2000?
Also something I dont understand and iv asked before and still didnt understand but didnt want to ask again is iv read you need to check the lifters for rotation which I understand why but how is that done while it's running at 2000 rpm? I can't see the lifters without the intake off?