Design Penalty for Switching Leagues

Would someone mind explaining what would happen in this very specific situation for me:

A group of us have joined a league which has yet to start, even though I am yet to take part in a race I have had 1 day to develop my car.

If we were to leave & join a different 2 car league which a friend of ours is setting up this weekend would we incur any design penalty?

I appreciate we that the season hasn't technically started but just wanted to check if improving parts acts as some kind trigger. I appreciate that this could be abused if you could just hop leagues between seasons whilst developing the car but as I say, we've only had 1 day of development thus far potentially 3 by the time we leave.

Thanks in advance

EDIT: Just to add, I did try an experiment by attempting to switch to another league & on the confirmation screen there was no mention of a penalty, should I assume that this means there isn't one?

For future reference, there was no penalty.

if the league you are joining has NOT started their season, then you will not incure any penalty.

If the league you are joing has started their season and is behind the league you are in in terms of race, your design will be scaled down.

This is incorrect. It's actually based on the league you are departing.

You can leave a league without penalty up until the first race of the season.

One of my teams finished the season in a "dead" league 3 days ago, after my search for a more competitive league i found one with the last race been held yesterday at 18:00 in the evening...so around 18:20 after their last race started i joined the new league, but i noticed that at the table i was showing as the last team with 0 points...so i was worried that my car developing would reset to 1% (because i join at the last race so i didnt have any car development until the new season's reset) i immidietly left the league and i join back after 3 hours without having any penalty...so in my case what it did count and i didnt got the penalty...?

I think there is an exception to the penalty regulation that goes into effect when you leave and then rejoin the same league without having joined any other leagues in between.

+ you didnt raced for that league, if you join and leave a league, without doing any race, there isnt a penalty, I think.