FLR(M) and MN1 Timing Query

Dear all,

I have just been given ILR on LR route 10 years (August 2007 - August 2017)
My wife joined me in UK in July 2010 as PSW dependent.
Our son was born in Sept 2012. He was also given the Tier 4 dependent visa.

Since 2011, I was on Tier 4 Student and subsequently from 2015, on Tier 2.

I understand that I am able to apply for naturalisation for my son as soon as I get my ILR BRP. Is MN1 the right form for that?

For my wife, do I need to apply FLR(M) even though she has spent over 7 years here as my dependent?
Her LR is not completed until July 2020, so if she is likely to require 2.5 years FLR(M), when would be the best time to apply so as not to have to apply for another extension of FLR(M)?

Your advice would be highly appreciated.