Paul;
If you installed the support files for Visual Basic when you installed NI-DAQ, you will have some good examples you can refer to on your hard drive.
To your particular application, you can take a look at C:\Program Files\National Instruments\NI-DAQ\examples\Visual Basic\Synchronize\Synchronized AI AO Counter. That example shows how to synchronize AI with AO after a fixed delay. You can use that as a start point for your application and change that so another AI task would start after a time delay, instead of the AO task.
Hope this helps.
Filipe