I think it depends on the individual as well as how often your periods are. If your cycle has started lengthening and you go eg 2 months between them then no reason not to start straight away at your age and if you are experiencing symptoms - and as dahliagirl has found this has been helpful from the start. Others find that sometimes the added oestrogen gives them too much when periods are still regular.
I started at around your age but my periods were very infrequent - had had a couple in the year prior to starting HRT and started HRT after 5 months since previous period. It worked like a charm from the beginning, for flushes and sweats - and apart from having to change type after 3 months, and a couple of goes at stopping/reducing - I have been on more or less the same oestrogen dose and patch ever since ( 10 years ago).
I did have a couple of years probably of worsening flushes and sweats which came and went when I got a period, as well as a bucket load of tears - and mood swings, but I managed to ride through these until the point I reached - in late peri-menopause when it was obvious the flushes and sweats were there to stay, and started HRT.
Hurdity x