I don't plan on using either when I cycle. Just my skimmer for mechanical filtration and live rock/sand for bioloigcal filter. Phosban is used to keep phosphates down to zero. IMO if you use quality salt and RO/DI water you shouldn't have phosphates. Commercially made fish foods have phosphates so one can eliminate or reduce them by feeding homemade foods. If you maintain your calcium levels (keeeping them high), it will help to naturally reduce phosphate levels. I also believe carbon can possibly leach phosphate (can't find my source on this). Carbon also removes trace elements but it does add to water quality. But your UV sterilizer will do this. UV sterilizers remove good and bad elements also but not all of them.
I believe all three of them could possibly mask problems in your tank. IOW if you test for phosphates and find them to be high it is best to learn why and try to correct it (less feeding, changing foods, bad water source etc.). I'm not against running either but favor using them on an as-needed-basis or from time to time.
If you feel you must run phosban and carbon, your best bet would be after your cycle. Let your rock and work alone and harder in creating their biological filtering capabilities.