What should be engraved on my sister's watch?

Being the first means being healthy and happy. Because of the name sister, you can know that you are younger.

1. Assuming that my sister is still a student, it is very appropriate to engrave "to beno. 1" on the watch given to her.

If my sister is no longer a student, you can write "Healthy and Happy". I hope my sister will be healthy, happy and happy in the future.