Timelines will vary. The most important thing is really to take it at your own pace. This is one time in your life where you should be 100% egoistic. This is something that you are doing for you, and only you. No interfering, no rushing. Do everything in such a way that you feel comfortable.
From my own experience, I worked with my therapist for almost 7 months (admittedly with long gaps between sessions due to her schedule and mine) before starting electrolysis, and another 4 months before starting HRT (month 3 now). Nice and slow really, despite the fact that I really wanted to rush it initially, but if I'm not going to let anyone else pressure me, then I sure as hell won't let me pressure myself either.
I was lucky enough to be friends with an FTM, so was able to come out to at least one person rather early on. My mother and I had "the talk" after about 3-4 months of therapy, and she is very supportive, as expected, otherwise I would have delayed that a bit further. Friends are gradually going to be told over the next few months.
Workplace is something you should start informing yourself as soon as possible. For instance I have to give our management a heads-up 3 months before social transition (i.e. full-time at work), which means I have to judge at what point I want to take that step quite a bit in advance. Also the policies in terms of job protection and discrimination are items you will want to look into, both in for your employer and workers' laws in your country.
Everyone is different, and there are people who would want to go full-time as soon as possible; but there are also ones like me who would prefer being misgendered while still presenting as male rather than the other way round. Go with what feels right to you. Doubts, worries, and confusion are normal, and a lot of it will start sorting itself out over time. One last piece of advice: even after you start HRT you may find that, often after about 6-8 weeks, it is maybe not the right thing for you after all. Again, listen to yourself only here. That is actually one of the reasons why I have been putting off telling some of my friends about it, as I did not want to create any weird pressure for myself to continue if I don't feel like it. The aforementioned "be 100% egoistic" strikes again.

Oh, and put off worrying about stuff like SRS for now. Generally you should be on hormones for at least 12 months before getting SRS or FFS, so plenty of time to start sweating the details when you're closer to the date.