By all means, add the majority of your extract just a few minutes before flameout. Start with a quarter to a third of your fermentables at the first hop addition, then boil the specified time.
Five to seven minutes before the fire goes off, stir in the rest. (Of course, you will turn off the flame while stirring in the extract, then fire on again.)
As for me and my household, we shall serve the Lord. Joshua
"God is great, beer is good, people are crazy." Some country artist