I will be hosting my first seminar at the school since the move two years ago and since remolding as well, a couple of question for everybody.
1) What is the timeframe before the seminar to start to promote it
I would say
at least a couple of months in advance - people need to plan; farther ahead (up to 4 months, I would say) would be good, but not so far in advance that people put off registering and don't come.
2) Do you need to have everybody pre-register or accept at the door registration
It depends on what you want - you may not get as many people if you only accept preregistration; on the other hand, preregistration ensures
some income. My suggestion for this would be to have a discount for registrations received (or postmarked, if they're being mailed) by a certain date, and a higher price at the door.
3) how mnay different styles can be done on a weekend seminar, I mean two or three or do they all need to be about the same
I think you will do best if you have some kind of a theme than if you try to put too much into the seminar. Is this a one-day seminar? 2 days? Friday night to Sunday evening? All of this will feed into your decision. But you should at least limit yourself to a broad theme - grappling, or hosinsul/self-defense applications, weapons defense, something like that. You could have multiple instructors from different disciplines teaching within the broad category, but I think if you try to put too much into it you'll weaken your focus and not get good attendance - it'll be a hodgepodge. If you want multiple styles, you might do multiple registrations, for people who only want one thing - say, rate X for Saturday, rate X for Sunday, rate Y for both, with Y being more than 1 day but less than paying for each day separately. Then people can choose what they want to come to, and can come to one day if they can't manage both from a scheduling or financing position.
4) Do you give a discount for early registrtion
See above. Generally, yes; it encourages people to register early, so you have some idea how many people are coming and can plan accordingly. We've started having preregistration only for many of our events because of the number of people who say they're coming and then don't show.
Anything else you would like to add feel free to dao so.
If you are opening this up to multiple schools/styles, you might want to give your own students/association members a discount for attending. You might also consider a family discount, or providing free registration to instructors who have a certain number of students register by the preregistration deadline - this encourages instructors to get their students to register as well.
Good luck, and let us know what you decide.