DS is 23 weeks and since 7 weeks old has slept through the night. He has been going through a period of waking earlier over the last few weeks with the occasional wake through the night. He usually gets a bath between 7.30 - 8 then in bed between 8.30-9pm. He would have slept until 8am before and now wakes sometime between 5am - 7am. Since the clock change he has been getting grumpy from 6.20pm my suspicion getting tired. We have stuck to the same bath and bed times but he is waking an hour earlier between 4am and 6am. When should we bed him now?
I would put him to bed at the normal time (time you want him to go). He may be a bit grumpy, but will survive. Alternatively you could try putting him to bed half an hour earlier for a few nights and then go to normal time.
Hopefully in time the mornings will adjust. However he is likely to be teething too (so expect some sleep disruption - on and off - for maybe a year or so). An older baby I would suggest "not starting the day" until 7am, but I think that your baby would be too young for that (maybe keep him in the dark and quiet, but feed as needed?)
(My son slept through from 12 weeks - I, very naively thought "that is that, he will always sleep through". I had a very rude awakening between 13 and 19 months - the worst teething time for us... We kept a mattress, duvet and pillow by his cot)
Personally I tend to work through the grumpiness and try to put him to bed at the normal time, but you are talking to a Mum who takes her DS to the US (normally West Coast) 2 or 3 times a year (since 5.5 months old), so I am used to adjusting clocks (time zones) and so is DS ;)
You may well get a lot of grumpiness from teething as well at some point, so hang in there.