There are two parts to guacamole, at least as I prepare it: Avocado and pico de gallo. It just takes a few minutes to combine the two, so keep them separate until you're ready to serve.
Basically, make the pico de gallo in advance and open just enough avocadoes for that one sitting. Next time you're ready for guacamole, open a few more avocadoes and combine with more of the pico. I recommend salting to taste, then let it sit in the fridge for 10 minutes or so. Then check the salt level again.
Pro tip: For spicy guacamole that doesn't taste like jalapenos, use a habanero. Hmm tasty.