You cannot do this with a DE full encapsulation.

The VFP sequence is not good designed and you have no events for set a flag :

FORM.DATAENVIRONMENT.OPENTABLES 
FORM.DATAENVIRONMENT.BEFOREOPENTABLES
* now VFP load de tables
FORM1.LOAD  && <== now you have datasession filled
* at this point VFP start the init form objects phase, and you cannot trap it until Form.init is fired
FORM1.DATAENVIRONMENT.CURSORS1.INIT
....
FORM1.DATAENVIRONMENT.INIT
FORM1.Controls[1].Init
.....
FORM1.INIT  && <== now you can unload the form

Fabio