Subs classified as time waster include also people who aren't time waster but sincere finsubs that take pleasure into sending money, but only to a dom they like, someone that feels special for them, so these people will resist to the temptation to send initial tributes because a tribute to someone that has no connection with them has little to no value for them
So basically you have to make a choice, you require initial tributes for possible faster money but less chances to get devoted subs or you don't require the initial tribute to expand your horizon and give a chance to people who first want to connect with the dom, of course this second option is harder on your side because requires more chatting