Leaving Batter w/Eggs Out?
Is this a yeasted batter? I can't think of any other reason to leave a batter sit for three hours. If the leavening is baking powder it will lose it's influence sitting for three hours.
Short answer to your question is, if the batter must rest for three hours, you could hold out the eggs and add them in later. But if the temperature is under 70 degrees they should be alright in the batter for that length of time and I wouldn't hold them out under those circumstances.