Milan Italy attractions: The Last Supper tickets - released in batches?

I’ve been checking the official VivaTicket site for The Last Supper for weeks and it just says “not available” for my dates in April. Does anyone know if they release tickets in batches? Or is there a specific time of day I should be refreshing the page? I really don’t want to pay 50 euros for a third party if I can avoid it, but I’m worried I’m going to miss out completely.