The investment plans are just exemplary. You can add and withdraw money at any time under the conditions described in How It Works. 
For simplicity they are listed in US $

Deposit $12.50 Deposit $12.50 - 1 Deposit $30.00 Deposit $30.00 - 1 Deposit $125.00  



Deposit $125 - withdraw Deposit $1,250.00 Deposit $1,250-withdraw Deposit $2,500.00 Deposit $2,500-withdraw