Started with 6,305xp/player.
Earned 8,000 total/5 = 1,6000/player
Therefore, 7,905 total per character.
4th level is 9,000xp.
Came into the session at 3rd level with 5,000xp. You earned 5,220xp for the night, therefore 1,305xp/player bringing your total to: 6,305xp. Level 4 is 9,000xp.
The PCs are 2nd level at 2000xp by the end of 1st session.