I never even know if eyes are open (pitch black!) so never used that as an indicator. I tended to use a kind of 'half A time' rule for that time in the cot lying awake calmly before getting up properly. So, if he wakes around 6am (or you think he might have done) but wriggles around, chats, seems to try to go back to sleep perhaps or whatever, and you don't get him up until 7am, then you could try counting that hour as just worth half an hour. So then if you're aiming for 2h then he could go down again at 8:30am. As he gets older I'd just start the clock from when he actually gets up, but opinion seems to vary quite a lot on this sort of thing - probably because every LO is different