Whenever suits you and her. The "norm" is cultural and 7pm is a peculiarly British thing. Please, feel free to ignore it completely if it doesn't suit you!
I let both DS and DD fall into their own routine. Both ended up going to bed about 9/10pm. That suits me fine as they slept to a decent hour in the morning. I'm not a morning person and I see no point in forcing my DCs into bed at 7am if they're then going to get me up at 5!
10month old DD currently goes to bed at about 9:30-10pm, sleeps through (she sometimes wakes for a feed, but we co-sleep so neither of us wake up much. As often as not, she doesn't wake for feeding these days). She wakes with DS and I for breakfast and the school run, then falls asleep when I return home, and has a nap for 1.5-2hrs so I have time to get on with stuff first thing. This is great as far as I'm concerned. She's had this paatern since she was really little.
When I only had one baby (DS) if I wanted to go somewhere in the evening (like visiting friends) I simply took him with me, in a sling or buggy. I can't afford a babysitter / nanny / au pair, and had I not done this I would have been trapped in the house after 6:30pm. DS came with me where I went, and slept on me or in the buggy when he needed to.
When he dropped his second nap in the daytime, he started sleeping earlier in the evening, about 9:00pm. Now he's at school he goes to bed at 7:30pm. There was no problem with adjusting.
I'm not saying you should have a later bedtime, but if it suits you and your baby to go to bed later, nothing wrong with this. It might also mean you partner gets to spend more time with them in the evening, and you too when / if you go back go work.
I started working when DS was 14 months. I didn't get back from work till 6pm, I'm really glad he wasn't in bed by 7pm, I would have hardly seen him.