Send requests as soon as possible
Send a vouch request as soon as you have finished the job, this gets the best results. Ideally it’s right after you finish the job is when the client has the most amount of appreciation.
Even if they don’t vouch for you straight away they will still have a mental note to do it for you in the back of their minds. So when they get sent a reminder which vouch automatically sends on your behalf they will feel even more compelled to do it.
Over 80% of all vouch requests are successful. There is no other review system which comes anywhere close to that.