I have on this check in form:
There is no proper way; a label refers to one element. Just point it to the first one.
You could also use a specifically-styled if you like semantics, but I think that's a bit overkill. An
is probably the best option here, as it is one element that can be pointed to by your
, is more semantic, and can be somewhat friendlier if you implement a good date picker to go along with it.
If you want to stick with the s, try giving each one a
title
attribute for accessibility.