Would be great if within TX (or via external script) you could trigger Data Source transfer tasks as an initial Step within an Execution Package (or batch), so that once the transfer of new data is complete, the execution package runs the next dependant step?  This way, if the transfer task from the data source to the DL takes longer (more data than expected) then the execution package won't run until it completes.  There seems to be no method currently to trigger a transfer load within the execution packages - and therefore no way to make the two different scheduling tools (it's really that) align with each other intelligently.