I come bearing great news. It only requires 8000XP to level up from Level 4 to 5. :)
Great news about level 4
I get that you're happy and want to show off, but it was mentioned already in Book of Answers / Chapter 4: Levels and Privileges
You get 70 points per day (if you don't count in the invites) so around 2 and a half months.
Luta Invite aren't worth much, they cap at 50/50. So at most 80+ exp extra.
BE THERE AT LEVEL 4 BY 2 DAYS.
Morinu Oh, didn't know that. Wasn't there before. :D