Since the events cycle is a little messed up because of the christmas events of the past week, rebate week could be show up on the week of January 4th, or even the week after that.

Since you don't have a lot of medium refines, stay with waiting for the rebate since 100 refines is to me a lot more than a weeks worth of free mount myoboku's gift and random prizes.

You understand that during a rebate you get wish credits once you level. After the rebate is over, the wish credits you gain from leveling from the event will disappear. So let's say you level an equipment from level 5 to 6, the rebate will give you 50 wish credits. Once the rebate is over those 50 wish credits will disappear.

It's better to do bulk jumps because of this reason as you'll more likely to level that one equipment to level 7 during the rebate week than spreading your refinement runes for multiple equipment and seeing the wish credits go to waste.