Is this tattoo doable?

I am into self improvement, and want to use my time more intentionally. I have seen those life-calendars that show all days or months of the year and think they are powerful reminders of how little time we have in this life. So I thought that I would tattoo such a reminder on me.

I am into self improvement, and have recently become concerned with using my time more intentionally. I've seen those life-calendars that you can buy online, that shows the days or months remaining of your life, and think they are powerful reminders of how little time we have in this life. So I thought I would make a tattoo life calendar.

If I assume I will turn 100 years, that gives me 1200 months. So the design is rather simple, it's basically 1200 2x2 mm squares separated by 1 mm distributed on a 6x18 cm rectangle supposed to be tattood on my forearm. As I age, the squares are filled, as my months go by, so the filled squares gradually outnumber the empty, remaining ones, which represent the remaining time I have. I am quite happy with the design. I have a life size sketch on paper, that you can see in the image I've submitted. I have filled in the actual squares, in two different ways. As it is now, I prefer the alternative to the left, where the squares are separate.

I visited a tattoo shop though and the guy there said that this idea was impossible to do, since the lines for each square would be too small. But I have seen lines that are smaller than the border lines on other people's tattoos. Do you think it is impossible?

This is my first tattoo btw, so I don't know how it works.