IMO you do not need to test your soap's pH. First of all it is very hard to reliably test the pH of soap with home equipment, false readings are common, and second of all soap is naturally very alkaline. Use a good recipe, run it thru a lye calculator of your choice, build in at least a little bit of superfat, measure carefully (in grams, not ounces), and make your soap.
After you are sure your soap has completely saponified you can do a "zap test", wet your finger, rub it on the soap, then touch your soapy finger to the very tip of your tongue. If you get a "zap" like from a 9v battery, your soap may be lye heavy. Rinse your mouth out, wait a week and test it again. Remember, soap that has not gelled can take up to a week to finish saponifying.
As far as when to test for skin safety, however you choose to test -- I'd wait for a day or two after cutting your bars to test the soap. If it tests skin safe, you're good. If it doesn't, then I'd wait a few more days and retest.