I've mentioned numerous times how the single most important factor in determining when you can 'retire' is your savings rate. To that end, I found a great early retirement calculator for you guys to check out and play around with.
You can adjust most inputs; income, savings rate, return on investment, etc. It is better than looking at a static graph for getting an exact picture of how long it will take you to achieve FIRE. I have had a lot of fun playing around with this thing. It's motivating too!
http://networthify.com/calculator/earlyretirement?income=40000&initialBalance=0&expenses=16000&annualPct=5&withdrawalRate=4
-The Money Monk
