Here would be my suggestion though:
When in doubt don't go with that early of a time. You're already having doubts that the toddler and the teenager being able to get up that early to make it. I wouldn't be making a reservation that early to begin with. I'd be pushing it to lunch or later in the morning (if that was available and that was the meal you were wanting).
You can modify the time and see what else is available.
In other words, in the most non-judgmental way I can be, to me at least the solution to your issue isn't to book several days worth of BOG for the purpose of cancelling them one at a time right when you're there. Usually when people do what you're doing, at least from reading the Boards, it's because they are waiting for their FP dates in order to shore up their plans. You however are going to wait until 11:59pm the day before when you're actually there at WDW. Normally when people do that, from what I've seen, it's one or two BOG they have held (I don't know exactly how many BOG reservations you hold), and this is why people can find BOG reservation the day of or the day before as people have cancelled them.
I appreciate your suggestion, and I have been coming to the same conclusion about our 8am reservations myself. I also appreciate your polite tone in the discussion about multiple reservations. I do want to clarify, though, that I am not sitting on multiple BOG reservations with the intention to cancel them at the last minute. I'm still far enough out that I have been able to move my BOG reservations (several, but with different groups, so I don't count them as hoarding reservations, since I'm taking different kids each time) between 8am and 9:30am a couple of times as I try to decide what will work best.
However, I do think that Disney's system encourages you to hoard reservations, particularly at the most popular restaurants, and that is reinforced by all the rhetoric in books, blogs and forums about how hard it is to get these reservations: it creates a scarcity and adversarial mentality, where if people are "luckily enough" to be able to grab multiple reservations 6 months out, they should book them all, because if they don't and their plans change, they will definitely not be able to reschedule nearer the time. I have read suggestions from other sources to do just that and, in all honesty, if I hadn't found this forum, I may well have hoarded reservations myself. When every other guest is being set us as your competitor for getting these highly-prized reservations, it really doesn't encourage anything but an "us vs. them" mentality.
Personally, the more hassle I have with making ADRs (which is a huge and ongoing job, as we are staying for 4 weeks on-property without a car), the more I'm taking the attitude of "this is the reservation, suck it up or don't come" with my own travelling party. However, none of these are my kids, so with the exception of the toddler, they will be on better behaviour with me than they would be with their parents. If the toddler doesn't cope then I will take her older sister and her mom can let the toddler sleep and meet us later. I'm no longer trying to please everyone, because there are just too many variables. My comment was more just to disagree with the suggestion that problems with ADRs were a result of poor planning, because while I think that is certainly a factor for some people, I feel that Disney has actually created the problem by deliberately creating a scarcity mentality in guests.