Hi Tom,
As soon as a lead is given the status of Registered within your Marketo program that's synced to the Webinar provider, that lead's information is pushed over. The {{member.webinar url}} token will be able to populate immediately barring any server issues, so a wait step is not really necessary. Some people do still include a wait step of a few minutes for peace of mind.
As Mike said above, the attendance information will be pushed back to Marketo after the event, but this can take anywhere from 2 hours to two days. It depends on when the webinar provider has it ready for Marketo. Also, keep in mind that leads registering on the webinar side will not be pushed to Marketo until the attendance report is pushed, so it's best to have all your leads register through Marketo. It sounds like your already doing that though.
John