I would also wait and see.  I started chemo and still had hair 3 weeks later,  it was thinner but not bald.  I had it cut shorter but that's it.  
After four weeks it actually became brittle and then broke off in places and my scalp was tender so I shaved it.  You may still have hair on your wedding day.  
I also bought a synthetic wig, a short cropped style which was very light.  Everyone says it looked great but I found it hot, that could have been the chemo though as I had lots of hot flushes. 
Congratulations on your wedding, hope your day is fantastic