It will come in time, but another thing that helped me when I was just learning was that its okay to strum without fretting a chord, but to remember to keep your strumming hand going anyways(KEpping in time), even if your fret hand isn't fully planted on the new chord. When playing faster strums(such as 16ths), it is common to strum during the change, just muting the strings by lightly touching them to deaden them

Gives your playing that chunky sound that many artists use. I also use it alot in rock with distortion(Along with palm muting with right hand).

Lisa can probably explain this better than me.

michael