We planned to start with a dozen - we were boarding for friends, so the idea was I would own 6, and each of 2 friends would own 3. When we went to pick them up from another friend (chickens she'd hatched from her own flock, so just a barnyard mix of chickens about 3-4 months old) she was fairly certain one was a rooster, so they threw in an extra. Cool. So 13 chickens. 2 ended up being roos, so 11 layers within a few weeks of us buying them. Then a family got in trouble for their chickens (a lot of places around here don't allow them) and they needed a home. So we adopted 3 roos (a sultan and 2 bantams - black japanese and quail d'anver) and 2 bantam hens. So up to 5 roosters and 13 layers. Sultan got eaten by a hawk.
Had a hen go broody and just for fun I stuck 4 eggs under her. 21 days later I had 4 baby chickens! Pretty neat. Over a series of a few weeks, we lost 1 of the bantam hens, 1 baby chick, and 2 layers to the hawk. Had another hen go broody and bought 5 sebright eggs to put under her. Only 2 hatched, 1 died at 1 day old, the other got out of the run (squeezed through the 1" chicken wire) and froze to death because it couldn't get under mama.

Mama was distraught, so I ran out to the hardware store and picked up 9 baby chicks - 2 light brahmas, 2 buff orpingtons, 2 gold laced wyandottes, and 3 silver laced wyandottes. Mama was happy again. Lost 2 of the wyandottes somehow (still no idea how).
Hit Southern States for their free chicks. Brought home 4 california leghorns, 3 gold-laced wyandottes, and 3 production reds (all for meat birds). Then added 5 broad breasted white turkeys. And 10 more sebright eggs in the incubator (although I'm only seeing movement still in 2 and we're at day...14?).
So all together I now own something like 34 chickens and 5 turkeys, with probably another 2 chickens in a week or so. The only consolation for my poor husband is that 15 of those are meat birds (10 chickens 5 turkeys).