When you are keeping up with your LOs milestones do you track months from the things they do up to the next month.

Example: can roll over at 2 months & 3 weeks. Since it happened in month 2 is it a two month milestone or a 3 month milestone b/c it was past the 2 month mark?

The first 4 weeks or the time from birth to 1 month counts as month 1, correct?

I’m probably the only one confused by this!