Hi Olivia,
We started EASY about the same age as your LO. If my DS woke up early, I'd try to feed him immediately and adjust our EASY routine with his wake up time for that day. Also, I'd watch for his cues if he got tired earlier and try to put him down earlier and readjust our routine. I wouldn't say to completely watch the clock but a mix of watching the clock and your LO's cues. I've also tried to start our days at a certain time 7:30 am but some days we start earlier and some days we start later, depends when LO wakes up. But I have at times had to wake up LO because of specific errands that we have.
IMO, by leaving LO in his cot until 6:45am, really you are doing AEASY instead of EASY. Thus causing your routine to be off. I based all my feedings/routine on the time DS woke up that day. So for your LO, his feedings would have been at 6am, 9am, 12pm, etc and it looks likes when your LO woke up at 8:45am he was probably expecting to be fed.
HTH