A lot of the bows w/ elastics use latex bands & that causes quite a bit of damage to the hair if left on for awhile.
I use the snag free bands, they're very stretchy & cut them off w/ band scissors. Re-do their top knot when needed. I sell these on my site if you can't find it locally.
This video is by a very good customer of mine, she demonstrates how to put a bow w/ elastics w/ perm paper. Enjoy!
https://www.youtube.com/watch?v=HqunQ6crjgM