If you have a form like the one in the image below, then you can use a jQuery code snippet to make the cursor jump to the next field after the user has typed two characters.

In this case, the code checks if a button has been pressed. Then, if there are two characters in that field, it simply selects another field by giveing it .focus();

$("#bDateD").keyup(function(e) {
		if ( $('#bDateD').val().length >=2 ){
			$('#bDateM').focus();
		}
	});

	$("#bDateM").keyup(function(e) {
		if ( $('#bDateM').val().length >=2 ){
			$('#bDateY').focus();
		}
	});