Someone else might have better info, but from what I can tell the lines are long pretty much all day. I heard something about an experimental ticketing system so people don't end up in 4-hour-long lines (essentially a placeholder in line for you) but I don't know much about it. That could be a rumor.
From what I HAVE read, you might have better luck in lines around lunchtime, with worse crowds in the morning (I hear they get rushed at rope drop) than you might expect. Don't hope to be in standby for less than an hour and a half, and prepare for up to 4 hours. If you go too late in the day you could get cut off, as they try to ensure that anyone already in line won't get turned away. This means that if A&E leave at 9PM and the line is already 3 hours long, CMs will turn you away starting at 6PM. They'll tell you that the line is closed or that A&E cannot see any more people today, thus allowing those already in line to see the princesses and preventing someone from waiting for hours and then NOT getting to see them because the park is closed. Keep in mind that princesses need breaks too! So even if you don't think the line looks THAT long, the CMs have to factor in breaks when estimating line times.
In short, if you can get those FPs, stick with them. It'll be risky otherwise. If A&E are not a big deal and the risk is OK for your DD, check line times periodically and don't wait TOO long or the line CAN close before the park itself does. 1.5 hr standby time is considered "good," so if you see that or less hop in ASAP.