So it is okay for him to have it for the week before the next check up?A long time ago, when geckos wouldn't eat we were advised to feed them baby food chicken. You're right that it isn't the kind of "meat" geckos usually eat, but it is meat. An alternative is to get some crickets and super worms and either kill them and squeeze out the guts, or (I know this sounds weird) put them in a blender and make a puree. With either method, if you dab some on the gecko's lips, it will probably lick off the food.
Aliza