Wicc
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It's very difficult to fit it into 3 days, and I'll have to take time off from work. 2 days is completely unrealistic. Therefore, unfortunately, a minimum of 2 weekends, and more likely even 3.
As I understand it, there are enough people for 4 rounds of a Swiss-system tournament, maybe even 5. This can be done in 4 days with plenty of time to spare.