Heine,
for that scenario you can't set up the execution order for workflows.
How it works
Below is description what happens behind the scene when workflow is being published in SPD.
While publishing workflow, for example using SPD, the new entry is added to the table Workflow Association that is used for storing information about associated workflows.
Below for the illustration purposes is shown the scheme for the table

To organize the execution order of workflows, potentially only two columns can be used:
Created
Modified
ID that has Uniqueidentifier data type cannot be used for sorting.
Further, when workflow is configured with Auto Start parameter enabled, SharePoint add the SPWorkflowAutostartEventReceiver receiver. This receiver is responsible for retrieving and starting workflows when list item is created and(or) changed.
On DB level for retrieving list of workflow associations stored procedure (SP) proc_GetWorkflowAssociations is executed.
But SQL select query for SP has no sort specified.
Conclusion
As a result, we can not rely on publication date. The order of execution is not dependent on publication date, because of:
- no sorting is used internally when list of workflows for execution are retrieved
- there is no possibility to specify sorting for SPWorkflowAutostartEventReceiver receiver
I recommend to consider a different approach here.
If you have a several workflows that starts automatically and have to be executed in ordered way, it possible to create the chain of workflows in such a way that next workflow starts after previous one completes.
For details please see activity Start Another Worflow