So from that I gather you must tell you tenant to move out within 6 months of moving in or he has the right to stay there for a further three years??..Very odd.
If your tenancy agreement/lease is binding for one year which I believe in the normal/regular period, you would then be in breach of that agreement if you asked him to move on before 6 months. The best you can do is look for and follow up references from your proposed tenant, be fussy about who you let your property to.