It will take ten years and four months.
At the beginning, the 4% interest rate will get you about 1 cent per day in interest. The interest will compound, but it will grow pretty slowly. When the principal plus aggregated interest has reached $200, you will get about 2 cents per day.
To get a total of $50 in interest, you will need to wait several thousand days — 3774 days to be exact.
You can get a
15-year table that shows the daily balance of your
4% of yearly compound interest like this:
"number of days", "aggregate savings";
sequence(15 * 365, 1, 0),
(1 + (1 + 4% / 1) ^ (1 / 365) - 1)
sequence(15 * 365, 1, 0)
The formula assumes that there are
365 days in a year.
To find the day when the principal plus aggregated interest reaches $150, use this:
=+filter(A2:A, B2:B >= 150)
See Compound interest.