Open periods of secondary ledger (SL) before finishing SL settings

I'm setting SL in production environment. I tended to not open first period until I finish all the setting. But now when SL was created , I can't post journals in Primary ledger (PL) because the status shows: the period of SL was not opened.

So I think I have to open periods of SL even the setting was not finished. When opening periods, to prevent journals from PL transferred to SL, I tended to do like this:

1. Disable subledger accounting and posting from subledger as below to prevent subledger journals transferred
   

2. To prevent GL journals transfer to SL , I set "No" for all manual source journals in "complete PL to SL" setting as below