Just a tip, but i would suggest an even number (my league is 6). That way, in the draft you chose your keepers the first 6 (in my case) rounds, and round 7 begins the new draft. If its a snake draft like most are, then the person who got last place the previous year can have #1 pick in the new draft instead of last pick as it would be in an even draft round.
i hope that made sense, it was a lot harder to explain than i thought it would be. If you dont do online draft, then it doesnt matter at all.