Fast,

you can speed that up by warming the epoxy before (or after) mixing. Keep your bottles near your furnace, water heater, or other warm spot (WARM, not HOT!) Or stick the bottles in the microwave BUT ONLY FOR ABOUT 10 SECONDS AT A TIME (they heat up very quickly). Or, mix them and warm it up with a heat gun (Again, warm, not hot)

Yes, it will thin it out and make it runny, but only for about a minute or two, then it will reach normal consistancy, but it will set faster.