No wori der brudah,
Well, that's also yes and no and maybe question.
YES: If you join a brand new progressive, yes you start from scratch, as do all of the other owners.
The commish picks a year say 1950 and a draft is held until all the squads are filled. Or the commish picks 2 years, say 1920 and 1970 and the owners pick from both years. In each case, the league then "progresses" to the next year, once the season is played out.
In scenario 1 (called a single season progressive) the next draft would be 1951, in scenario 2 (called a dual season progressive) it would be 1921/1971.
NO: You take over a team in a current progressive. Say the Centenary League, you then adopt the franchise and all it's current players. You analyze the team needs, future outputs, draft position etc. Then it's decision time. You decide who you want to keep or cut and prepare for the draft. For example. Your new team has 24 usable players (1 retired). After looking at the rest of the players you decide 3 do not have any use for you, so you cut them. Think Dale Murphy's last season.
That leaves 4 openings on the team. So you have 4 draftpicks to make. Most drafts are "off the clock" the 1st round. You make your pick and sitemail next in line. Starting in round 2, they are usually timed in 1/2 hour slots.
MAYBE: Take the above NO response and the scerario is that you take over a decimated team. Alot of retires/useless players/players on IR. You may need to draft 1/2 a roster or more. So in that case you'll need to do alot of research for the upcoming draft to begin rebuilding the team.
I have been part of all 3. My 2 cents is to take over an existing team for your 1st try. Be carefull, they are addictive.
As I only half joked of last night, you should check out the Centenary League. We have a great core group of owners who are longtime members and helpfull w/ q's. Our current season is 1992 and were getting ready for the playoffs.
Check out the thread in the regular team classifieds.