[bailey]

In your league settings/options
set the season start date to March 29 (or whatever you want)
and check the box to force start on a Sunday.

Also, uncheck automatically schedule all-star game.

To get the correct interleague matchups, your team IDs must be
1-5 ALE
6-10 ALC
11-15 ALW
16-20 NLE
21-25 NLC
26-30 NLW
within each division the cities must be in alphabetical order.
These are Team ID by default if you click on "new standard game" from the main OOTP screen.

Each schedule is 183 days long.