OP I could have written your post word for word three days ago, DD also 7mo and waking at 4 (or between 4am and 5am).
This has been going on since we started on solids proper. Occurred to me that she was waking at that time STARVING, so maybe she wasn't eating enough during the day? Then read something on a website saying that there is no need for a baby older than 6mo to wake in the night for food.
So, since Weds, have been getting her to eat more during the day - never stuffing her, always stopping when she says she's had enough - and so far (only been three days, but still!) she hasn't woken until 5.30am, after going to sleep at 7.30pm. So am going to keep with it and hope this sticks.
Incidentally, she eats porridge with fruit puree around 8.30am, milk around 9.30, nap 10am to 12.30pm, banana (whole thing!) with a bit of milk, nap 2.30-4pmish, rice with veggies and meat/chicken and more milk around 4.30pm, yogurt around 6pm, bath at 7pm, milk and bed.
Like I say, keeping fingers crossed!