I own a home - can I create a joint tenancy?

[Maxym Le Deux]

I'm trying to understand the feasibility of this scenario.

I Live in CA, solely own my house and share it with 2 tenants. I would like to include my tenants as "Joint tenants" 
with right of survivorship... splitting the house equally. In my county "Joint tenancy" does NOT trigger property tax reassessment which I would greatly like to avoid. I understand "Joint" must meet the 4 unities (Time, title, interest, possession).

Since I already own the house would the "Time" aspect prohibit the creation or is it possible to still do? I will get legal advice but I hope someone can help answer this question so I can navigate the legal route a bit better. 

Thank you