The way the other refine event works is you get a fixed amount of wish credit towards the next level when you finish a refinement level up. So during this event you ideally want to get everything up to 30-50% and then wait until the other refine event comes around so that you can finish of the refine level up to get the wish credits towards the next level.
Basically as long as you're spending refines but not leveling up during this event you're losing out on nothing. And if you unexpectedly happen to get a lucky level up from a very low %, you won't get wish credits but the amount you saved from good luck partially makes up for it. The main thing is to be careful leveling up refine level 6 items because 6 -> 7 gets you advanced refine rune credit.