I didn't see the prompt to press Start/Tab for button prompts at all during my first time fighting the tutorial fight. It's on the upper-right hand part of the screen when all the new HUD stuff you're taking in is in the center.
Similar issue with the very first dialogue option--there's no indication that I can see that you select dialogue options with A/X/Y/B instead of the d-pad. I can figured it out, but y'know, confusing.
Please consider integration with the Steam Controller API. I use a Dualshock 4, and hey buddy, these Xbox button prompts mainly serve to confuse me.