This is the link you found:
http://www.acvbus.it/orari/365.pdf right?
I'll offer some tips on reading the schedule since this is the format you'll find all schedules in and it will be useful to learn how to read them, for buses as well as trains.
At the top of the page, you can see a list of towns -- it tells you the order, so the first seven pages start with Gaiole and end with Florence, so those are schedules to get back into Florence.
The far left column is the stops the bus makes, it generally makes a stop, picks up people and continues on its way. So the times are generally when to expect the bus at that stop.
You see it makes two stops in Greve and several in Florence. The main stop in Greve is right in front of the public library, in front of the Fuori piazza pizzeria/enoteca - here's a view:
https://goo.gl/maps/jMAz7wWrpBn
At the top of the columns, there are some that say:
LUN-VEN --- means these buses run Monday-Friday
SAB --- runs on Saturdays
FESTIVO -- runs on Sundays and holidays
Nov 2 is not a national holiday (the day before is) and it's a Wednesday so look for columns that have LUN-VEN to identify those as the buses you'll find running that day.
I see there is a bus at 18.15 (coming from Panzano so this makes a stop and continues on) which arrives in Florence by 19.15 and another at 18.55 (which starts in Greve) that arrives in Florence at 19.50. So yes, it seems you can stay in Greve until late evening and then return to Florence by dinner time.
As for getting there, you can now take a look and see which bus you can take from Florence ;-)