Hi - not long at all.

Why did U begin HRT, which symptom would you like to ease first?
Bloating can be part of the menstrual cycle and may well be aggravated by HRT. I have suffered with low transit for many years, 10 mins B4 a bleed I would have to rush to the loo Or Else even if a period wasn't due !
Make sure that you keep hydrated and mayB eat light meals for 24 hours to rest the digestive system. Let us know how you get on.