BunnyBee seems to sum it up pretty well.
For me, I guess mark 1 would be when you can "pass" consistently, and mark 2 when you can truly feel comfortable with yourself.
I've been trying to gather money for FFS and SRS myself, hopefully I'll be able to get FFS done this year still, as I often feel dysphoric just by looking at my face even if I "pass". Again for me, I guess I'll consider myself done with transition after SRS, even if I still have transition-related business to complete by then (such as finishing electrolysis, or legal name and gender changes).
Also, here in Brazil - which has been going quite slow in the legal department still, most of the time you can only get a name change either after SRS or with a lawyer - a famous transsexual woman named Daniela Andrade recently sued her health insurance and got them to cover
everything regarding transition. Granted, she did it with a lawyer who's become quite the pro at transgender legal issues, but it might be a possibility if you have an institution who can act as a lawyer for you and has experience with transgender rights.