6 weeks for a suspected active infection as due to the cyclical shedding and environmental survival duration of the spores it's possible for a rabbit to re-infect themselves on 28 days.
Partners whould be wormed for 6 weeks too.
I would say the 10% oral solution is going to be best value for money, about £13 for 100ml and the dose rate is 0.2ml per kg of rabbit.