The board game Risk has a rule, or at least it used to, where if you're going 5th or 6th you start with bonus cards to off set being inactive on the board for so long.
Your app really needs this feature. I'm often last when setting up games and have to sit around watching every other player chip away at my territories before I can even move. The players that go 1st-3rd have such an advantage baring a bad dice roll. Have players who start 4-6th get bonus cards to replenish their forces, 4th players get 1 card, 5th and 6th get 2. This would balance out having to start later in the game.