They can go without water until they start to visibly wilt - if you think they are getting close SHUT THE FAN OFF to avoid damaging leaves. (Run the fan until the top 1/2" of soil is dry, then go ahead and stop it until they get full dry).
Once they begin to wilt you have about 12-24 hours or so (assuming no wind damaging leaves) to re-water them and not cause any permanent damage.
The BIG leaves will be the ones which will visibly start to "thin out and droop". Try not to handle those AT ALL and water very carefully around them; the leaves get very, very fragile when they start to wilt.
I've had pots I thought were BONE dry not show signs of wilting for 2-3 additional DAYS. It's very easy to over-water peppers. It's very difficult to underwater.
Once you add water (carefully) don't be tempted to super-soak them. Add about half of what you'd normally add, and watch them. If the leaves don't start perking back up and filling back out in 4-6 hours, add a little more. You can always add water. You can never really take it away.
Depending on your soil the water may pool on top of the soil when you re-water - that's fine, and makes it easy to measure - just add about 3/8" of water (depth) and let it soak in on it's own.
When the leaves plump back up you can restore the fan; it shouldn't take long, just a few hours and they'll start looking good again.
What I do after this you may or may not want to do - I let them go dry and wilt AGAIN.
When I do this, I learn how FAST they are really using water, and then can water the appropriate amount. I cut the amount I normally water in half, and cut the frequency from wilt/water/wilt in half.
So if they wilt, and I gave them 3/8" of water on day 0, and they wilt again 4 days later, I'll give them about 1/4" of water (depth) every 2 days. (If you have a turkey baster you can also measure by volume that way).
Hope this helps!
How fast they dry out depends almost entirely on the size of the plants, and the type of pots and soil you are using. Some soil holds more water than others, and bigger plants use more than smaller plants.
If the soil is TOO saturated or holds too much water, the roots will begin to rot. The water acts as a buffer, and closes off all the air gaps in the soil - without oxygen in the soil the plants' roots can't do their work and pick up nutrients! The water will stagnate and mold will form, eventually killing the plant.
Let them dry.
if you have any doubt about how WET they are just pop them out and feel the soil. It should feel moist, NOT soaked.