Won't it better to make the potion dropped in wilderness like the map too or give more potion so that at least player can have more chances to get the full reward?
You will obtain 1 option a day via the IG mail. I believe that the developer did not intend this event to be rushed through and be completed in one day. Take your time end enjoy it rather then stress out over it... Its something neat on the side
If you must rush it, the potions are available in the item shop for your convince for both, gold and gems.
FYI, today's potion just got send out!