I would be far more concerned about the lingering effects of the insecticide, not so much the fertilizer.
On a side note, as a Certified Horticulturalist (by the Virginia Nursery & Landscape Association) I can tell you that this is NOT the time of year to be fertilizing your lawn, and any insecticides applied now would be of limited use at best, if not a complete waste.
Contact the county extension agent for more information more specific to your situation.

