No, You are wrong. It's 55 days, it's simply calculation. To build arena we need:
[(1x Bleachers + 1,5x Lower Tier + 2,5x Courtside Seats + 4x Luxury Boxes + 5) / 250] days (rounded up to integer)
If arena is built gradually then of course we need more time, however in this case incomes in first season will be higher than mentioned in previous posts.
And 16 weeks without salary floor means 11 weeks with arena revenues only in worst case (when new team is created just before play-offs). In typical case it means 13 arena revenues. However, in these 3-5 weeks without arena revenues, new team in 1st division should have Typical Weekly Net Income = 150-200k. So if we consider all these facts it means that new team in 1st division should have more than 4M, not 3M after 16 weeks. And few wins with bots in cup should give few dollars more, and new team still can sell players and make extra money. I think even 5M is possible after 16 weeks.
an another note~ my motivation is to have domestic competition. I WANT new teams to be able to challenge me in games as quick as possible.
New teams in small nations are competive much faster than in big countries. In whole history in my country only teams created in 3rd season won 1st division. With Your knowledge and with team created in 12th season You would play in IV division in my country. Meanwhile in Your country You can play in B3 only because Japan is micronation.