I always start flask + wards & rush sightstone. The flask gives me all the sustain I need, it's worth several minutes of regen from a philo except you can get it all at once and refill when you need to. Early game can be a bit hard if you aren't careful not to drop wards too early (or late...), but most junglers don't seem to gank as early as they used to and I find that I have a bit of time to ward river.
I think it's ~7 minutes that I need to make it to for sightstone. Of course, if there's trouble I'll be sure to buy more wards before that to tide us over, but most of the time I can stretch the initial wards out until I have gold for sightstone. If you get an early assist, you can usually get a faerie charm first back, too, and it's easy from there.
Granted, I'm Janna so boots can wait for a long time.