Numtel:mysql subscription callback

I’m trying to export some data from a mysql database to text files on the server-side (using the numtel:mysql package).
Basically it looks like this:

'exportSomething': function(variable) {
   .. export data from subscription ..

The problem is, the subscription is lagging behind, since it’s not ready() by the time the export code runs.
Is there a way to wrap my “export data” code in a callback, like I would do when calling a server side method?