With the current version of EB (3.17.2) you can only give discounts based on number of tickets (
eventbookingdoc.joomservices.com/plugins/ticket-types
)
With Standard Tickets you can give discounts based on Member Discount Groups (see screen shot)
It would be really nice for each
Ticket Type to be able also to give discounts based on Member Discount Groups and Early Bird Discounts