I get this question a lot. And my answer? It depends on the type of event you are holding and for how many people.
My rule of thumb is:
For small and medium sized gatherings with up to 100 people at a lower cost (eg. under $100), 8 weeks can suffice if you have an audience who are keen to work with you.
For events where you want more than 100 people in attendance or premium events for smaller groups but with a higher ticketing cost such as conferences, retreats or mastermind sessions, I would start promotion even up to 4 months in advance.
This doesn't mean you have to sell tickets that early on, but it does mean warming people up to the idea through Save the Date's, teasers and newsletter or social media mentions.
Here are a few things to consider when thinking about when to open ticket sales:
+ Do you have a mailing list or engaged social media network that will buy most of your tickets without too much effort?
+ Are your tickets going to require people to look at their cash flow over the next couple of months to see if they can afford it or are they priced at a Buy Now rate?
+ Do you require a lot of lead time in order to prepare materials/presentations/accommodation etc and need to close off sales well in advance of the event?
+ When do you have to give your venue or caterer final numbers and when do you have to pay the full amount for their services?
Think your demographics level of interest and cash flow, as well as your obligations as the event organiser to the venue and suppliers.
If you plan in advance, you can make sure that your ticket sale timings reflect these responsibilities.