the curse of the C chord was a nasty one for me for a long time, most because i didnt even notice i was doing it until it was too late
unfortunately it's the old addage of practice makes perfect.
stick with it and it'll work itself out :-)
This is my signature. Fear it.
Try switching back and forth from the C to G7 (BTW you can get some nice tunes worked out with just these 2 chords). Both chords use the same 3 fingers and are just one string movement away from each other. I think once you get all 3 fingers working at the same time you can add other chord changes to and from C.
Run slowly through a progression say “G-C-D†playing it bass-strum style. I was always planting the index first when forming C, so playing bass-strum style forced me to get the ring finger down on the A string quicker. So play the G-C-D progression in various orders in this style and eventually your fingering will improve greatly.
I had the same problem with open C when I first started. So I just started concentrating on putting my ring finger down on the 5th string, third fret FIRST and then moving my other two fingers into position. Go from G and D to C, concentrating on putting your ring finger down first when you make the C. For some reason, once my ring finger was down the other two fingers were quick to follow. After a while, they all just started moving at the same time. I read about this tip on another message board and it worked for me so I figured I'd suggest it to you.