Now that FT is deploying, it’s important that the numbers of people onboarded, using the service, and signing up for Alpha all grow quickly.
Consider moving the reward further down the customer funnel: if the newly referred user makes a first trade/makes an instant trade/signs up for isa/signs up for alpha then give that new user and the referring user a free month of alpha. (If the referring user already has alpha, give them a one month rebate.)
Would have the side benefit of encouraging both referrer and referree deeper into the product.
(Related: How many people in the queue are seriously going to use FreeTrade? )