Does activating a character make a difference?

If you have enough shards to unlock a character always check if he can be pulled. If he can't be pulled you might as well activate him. But if you can pull him from packs try and wait with activating until you get the pull. The shards you already will count towards the next star upgrade.

For instance if you have 80 Daka shards wait unless you really want to use her. If you pull her you can immediately promote her to 5* ;)