I can answer this, I've just been through the Status Hold process with both VA and QF.
I had VA Plat through the Business Flyer match last year. I was going to drop to Gold in late March, and called to request the extension in mid March shortly after my daughter was born.
My status went on hold immediately when I called - no documentation required for first request. I was told that once my status resumes, I will have another 12 months of Platinum to hit the 800 SC retain target. I will actually be doing some personal travel during the 6 month hold period and have no idea whether these SC will carry over once my status is unpaused.
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I don't know how late you can request the hold, but with the dates you've mentioned, your strategy sounds good.
Happy to chat through the QFF process also if you have any questions - PM me.