Hayley, well my kids have been waking up early too (Danielle was 5.45 today) - roll on daylight savings!!
So, today she actually needed a 2nd morning nap because of the same problem. She went down for a nap at 7.45 and 10.45 for 45min each and then 1pm for 3hrs and will be awake from 4-7pm.
Danielle doesn't really show tired signs much anymore, but does rub her eyes but she can keep going for another hr or so, she doesn't grizzle, but does maybe need me around her rather than independent play at that time of day.
It is confusing, but I think they figure it out, if Daniel is melting down if he's been up too late, then you will definitely need the extra nap still.