My easterns that have laid eggs have both started digging at about 7 or 7:30pm, laid and positioned eggs in the nest between 9 and 10pm (or so), and were in the later stages of covering the nests at midnight, at which point I went to bed, so I don't know how much longer they were at it.
I have no idea if thats typical or not, since I have come across a wild turtle finishing up at 8:30am, and another who was finishing up by 9pm, but in all cases they were working under some darkness(at least part of the time).
The actual egg laying didn't take very long at all (20 mins or so for 4 eggs), and there are lots of variables.
I had had a sprinkler on in the enclosure yesterday morning for about two hours, to water the plant material, which ended up being a great help to Millie who laid last night (2nd clutch).
If you can put her outside in some sort of enclosed space and let her do her thing without disturbances or interruptions, that would probably be best.