Application code residing in the EPCS

I second Jesse's statement. There is no perceptible delay from hitting reset to the code running. The only problem you might run into is the size of your app. I'm using a Cyclone C6 and my code is under 200k and it uses 3 sectors of the EPCS. You might need a larger device than the EPCS4. I'm told that there are other serial flashes that are pin and protocol compatible with the EPCS series. But, I don't think the Altera tools support anything but the EPCS1 and EPCS4. Good luck.