I guess u're not that much online ? Free player here, started this event with 0 peronamins, and level 35 or so (now 40 ) so not that big of stamina either. Now i am at 47 k bouquets (around rank 310) so soon will get that 50k, and made a little namin stock.
In my opinion is best to rush to Ex stages as fast as u can, because 2 of the prizes from completing an Ex stage are 100 and 300 bouquets among other goodies. And ofc stalk those pink cases as mad xd