If you're using the primary only, I prefer 3-4 weeks total in the carboy. If you're using a secondary, you can do 1-2 weeks in the primary and 2 weeks in the secondary. The temp. is crucial in the first 5-7 days. You want it to be in the 60s for this style.
For an American IPA, I like the 62-68 F fermentation range... especially with the typical California Ale yeast. If your IPA already fermented at 75-80 F, then it will not get better. When this yeast is fermented at high temps, you get more fruit and less citrus. Some of that fruitiness will be from Amarillo, but most will be from fermenting high. So most likely, what you did is already done. The only betterment for an IPA would only be from a proper conditioning/carb time and temp which won't take away from the fruitiness per se. I would shoot for 17 days at 72-74 F before you put the bottles in the fridge.