Page first, then invitations
The order of operations decides most of the outcome. The usual mistake is announcing a session before the page exists: the interested person has nothing to click, and interest does not wait politely. A draft page is invisible to guests until you publish it, so the honest sequence is build, publish, invite. Everything below assumes the link you send already leads somewhere real.
The shape of the product simplifies the plan: one webinar page carries one session — one date, one link, one list. There are no series and no multi-session pages here; a second date is a second page with its own invitation, and mixing the two is how lists get confused.