The other over the next few days.
It seems to me that I should have more coins ...
Current rate is 25% per year (365 days)
Which Breaks down to % 0.0684931506849315 per day, and the earliest you can stake is 20 days,
20 days * 0.0684931506849315 = 1.36986301369863
So if you have 10,000 coins in a block and it stakes right at 20 days
10,000 coins*1.36986301369863% = 136.986301369863
But if that Block of 10,000 coins does not stake til the 25th day then your numbers are
25 days * 0.0684931506849315 = 1.712328767123288
10,000 coins*1.712328767123288% = 171.2328767123288
If all of your coins stake at 20 days the interest amount seems lower , but it will stake more times in the year and interest will be included in the 2nd and beyond stakes increasing the final amount.
That how it was explained to me, anyone have a different opinion chime in.
P.S.
Write down the amount that is being mined and calculate the days since received and you should be able to compare calculations with amount received.
This is a rough estimate, You would have to Calculate by Hours & Minutes to get an exact match instead of days.