DO NOT UNDER ANY CIRCUMSTANCES "sign over" your assets to someone who has not earned your trust.
I'm not talking days, weeks, or even months here, but a minimum of two years of having a solid, trusting relationship. If you have many assets I would also consult a lawyer who specializes in personal trusts. The man should also consult a lawyer in order to draw up needed legal instruments to assure that his property is maintained in the event of his death or other incapacitating event.