I believe that vRA syncs with vRO every ten minutes (Infrastructure -> Integrations -> vRealize Orchestrator). I think that is the same schedule that the extensibility section updates its workflows too.
Although, we have had to wait maybe 2 sync cycles in the past. And sometimes having to increase workflow versions before they are available for subscriptions. So maybe it's a different sync cycle, or maybe there's additional processing that needs to happen before they are known to subscriptions....or maybe there are (have been) some bugs in the process.