Upgrade to family plan on apple music while on a free trial I got a 6 month free for apple music

I have a 6 month free for apple music, but I wanted to upgrade to the family plan as well. I was wondering when I upgrade to the family plan, will it charge me after my 6 free months of apple music or will it charge me immediately? Does it charge the difference between the free plan and the family plan for the 6 months or the whole cost of the family plan?

Trying to take full advantage of the 6 months free while giving my family the chance to enjoy it as well.