Unless stated otherwise, most bets will let you enjoy free bonuses as long as you have made your first deposit. Also, if it is said that payments made via CashtoCode are eligible for deposits, then you can go ahead and claim yours.
In many cases, the deposit, once approved, will remain valid for a given period over which you must use it. Therefore, be sure to confirm this information right after you have claimed your bonus on the betting site. As long as you are qualified, be sure to claim your bonus as soon as your payment is processed.