First, you should invest in some FUN tokens because they are very cheap currently, hence you will get the premium membership perks for a very small price, that is to say a cashback on all your bets, an increase of your daily interest earnings and some daily free WOF spins(currently suspended for most people though). Then you could try to play your bonus during a 6hours flash promotions, to get the rewards of the flash promotion on top of those of your bonus.