Illustrative example. The dates and amounts below are provided for practice.
A family wants a private record of 100 completed days after a birth on January 1, 2024. The number is a day offset rather than a monthly age.
Enter Starting Date January 1, 2024, choose 100 Days, and select After starting date. Target Date is April 10, 2024, Wednesday.
Decide what the celebration counts
The date is 100 elapsed days after birth. If the family calls the birth date Day 1, inclusive Day 100 falls on April 9 instead. To reproduce that target, choose Custom Milestone and enter 99 days after the start.
The leap day in February is already included. Do not add a manual leap correction.
Save a private marker
A neutral title such as “100 completed days” can be enough for a local record. Enter it as a one-time milestone rather than an annually repeated birthday.
Remaining Days is measured from the browser's local current date, so the target date is the stable part of this example. A future screenshot may show zero remaining days because the target has passed. That does not mean the original calculation changed.