Thanks so much for your help.
I did not find any date indicate H4 effective date on 539 form.
-You do not need to put the effective date of H4 in the form. Let USCIS decide that.
question again for part 1 expire on(mm/dd/yyyy)?my 797 approved until 2012/10
-Correct.
should I put the date lost job here? if I put 2012/10 here, where I can indicate H4 effective date?
-Not need this information.