Massachusetts Eviction - What if tenant is late with rent?

[Zoltan Fagyal]

Hi Everyone,

Let me start with a possibly silly question. I'm in MA and may need to evict my tenant. I read a lot about the written fourteen (14) days notice to quit, and I read that the tenant has 14 days to pay or move out. If that doesn't happen I can start an eviction case against the tenant. 

My question is, what's the earliest you can serve the 14 days notice? Is that also 14 days, or different?

My second question: What can one do if tenant is always late with rent but pays first two weeks?

Thanks for your help in advance!