Late Rent

[Timothy Meuse]

My tenants have been in place on my first rental now for about 6months no issues so far.  On the first of every month my rent check is put into my mail slot on my door, however today that did not happen.  It may be something as simple as they didnt realize it was the 1st of the month however I would like to set the tone now. My question is should I draft a 14 day notice to quit tonight and deliver it to them tommorrow regardless of if I get the check by tommorrow just to show im serious about being late? Should I give them a 3 day grace period before giving them a notice.?They are great tenants a retired older couple that meet all the rental requirements and I dont think they even realize quite yet that the rent is late.  If thats not the case I just want to be proactive and get ahead of this before it becomes an issue. Any advice would be helpful, oh and by the way im located in the Tenant Friendly State of Massachusetts as well.