Here are some ways to improve your bases timing:

1.) Practice without the flier - Have a back spot place their hands in the bases hands, and simulate an elevator OR basket toss.

2.) Keep and eye on one another - Don't look right at one another, BUT make sure you can see the other out of the corner of your eye.

3.) Go for it - If you hold back, then it becomes uncertain how hard OR fast you are going to do the stunt each time.  Make sure you go the same speed (full out) so that it is easier to pick up the timing and make adjustments.

4) Change your stance - If the other base is taller OR stronger than you, then give them a wider stance for the adjustment.

5.) Fix the flier - Make sure the flier is NOT placing too much weight one or both of the bases.  It becomes difficult to pick up the timing if the flier is being lazy.  Make sure she is doing her part and pushing herself up.