Board Thread:Question and Answer/@comment-27892764-20160415171653/@comment-27860903-20160415181026

When you want to. But I suggested you to open them when you stop playing for the day or after a stack of 10-20+ then clean your present box until there's only SR/UR/slimes

N => Sell / Goddess worshp / Delete from presents box / upgrade slimes (mostly doing 2 first because lvling slimes with F/AW battles thanks to Fortuna)

R => Goddess worship / medal

I only keep SR/UR in my present box, I have 130 deck space & using 97/130 with 18-19 slimes lv 30, at this point you should have only SR or above in your deck unless you keep R because they're your first R or for the art