Hi Andre,
I am an Event Organizer/Planner with over 15 years' experience in organizing events globally. I have organized all types of events from conferences and roadshows to training sessions and retreats.
Based on purely organizing logistics for your seminars (venue finding, all liaison/correspondence with venues and suppliers, set-up/equipment/catering, staffing for the event, arranging any deliveries of presentation materials, travel logistics for staff participants etc), I would expect that it would take up to 2 weeks to organize each seminar. Not necessarily 2 consecutive weeks, but 2 weeks in total, as things like venue finding and venue contracts will need to be done in advance, whereas there are things such as confirming catering that can be done nearer the time of the event.
Ordinarily Event Planners work on a day rate basis as it is often difficult to put an exact time on the planning process, as there is an element that will depend on how quickly others respond to you, like venues providing quotes for example. For the purpose of this proposal I have quoted an amount per week.
Regards
Keisha