Hi nello.ianiro,

In my Guitar Fundamentals I Course, I go extensively into "chord-change-strategies". 

I appreciate Dave's suggestion of using a metronome, but before one can make a chord change "on-time", one has to learn how to make the chord in a strategic way. 

This means studying the relationship between the F chord in the music, and the chord that comes right before it.

Do the 2 chords share anything at all in common? 

You can practice "Chord Pairs", which means - select 2 chords (one of which is F, in your case).

And you go from Chord #1, to F, over and over and over. Slowly - trying to get used to the choreography of the move. 

Some suggested pairs, for starters:

C to F.   G to F.  Am to F. 

Hope this helps!  - Lisa