I'm up with DS2 now in similar circumstances 5 months from where you are now. Get it under control now whilst you can. It is better he is a bit tired at work for a while than you suffer ongoing.
Take your DD downstairs into another room that you leave a pillow and a duvet in before you go up. Shut the door, put a small lamp on (low light, soft light, dimmer on), lie down with her and ignore her. Sleep as much as you can. Harsh sorry.
Dd has always been an early riser-from about 3-4mo we were up at 5-6 every day.she's now 7mo and for the past month or so has progressivley been waking earlier and earlier,for the last few weeks she's been up and raring to go at 4am.it doesnt seem to matter when she goes to bed,what time her morning nap is,or how long she sleeps for during the day.she usually naps 30-40mins at a time,but rececntly has had a couple of 1.5hr naps mid-morning which has never happened before!how can I get her to sleep til 6???she's obviously exhausted when she gets up-rubs her eyes,yawns and doesn't want to play by herself,just wants me to hold her whilst she plays with a toy.I would quite like to do cc for the moening (does it actually work in the mornings too?!) But dh gets in from work very late and has to be up early the next day so every second of sleep is precious for him (hmmm sounds familiar..!),and the crying disturbs him..any wise pearls of wisdom from someone whose been there done that?