Hi sr-bmxdss, welcome to the community.
Recurring webinars can be scheduled for up to 12 months in advance maximum, however, as you start hosting those webinars you can add additional sessions. For example, you schedule a webinar to happen once a month starting in January with the last session in December (as the system will not let you go past 12 months). After the January session, you can edit the webinar and add another session for the following January. You can add more sessions whenever you want but they cannot go beyond the rolling 12 month window.