...escorts -- i.e. expensive female sex workers by appointment, as opposed to brothel workers, bar pickups and the like -- are generally believed to have low STD risk and frequency. They tend to know the score, know how to protect themselves, have relatively low risk clients (men like you), and get tested frequently.

...it would be reasonable for you to have blood tests for HIV and syphilis and a urine test for gonorrhea and chlamydia; and plan on repeating these every year or two as long as your current sexual lifestyle continues. When to be tested? Given your cumulative risk, you could do it at any time. But if you want 100% secruity about your most recent exposure, gon/chl urine testing can be done after 4-5 days and syphilis and HIV blood tests afer 6 weeks.