IRONMAN with no training, Tips/tricks to get through the day

Hi r/triathlon, Marcus (27) AUS looking for some tips on triathlons before I tackle this very naive and stupid challenge. Backstory - I've signed up for an ironman in October and I have never done any endurance training or dedicated any of my time to physical fitness... ever... Ive worked as a tradie for the last 10 years so I'm active all day and from the surface I look to be in peak condition, this has prompted me to make a bet with a friend of mine that I could complete an ironman sub 17 hours (the cutoff time) I know its going to hurt, that's fine. I just want to be able to "Do it", (heck even 80+ year olds do them sub 16 hours.) so my question to you guys is, what do I need to do to "survive" this event.

- Nutrition on the day, electrolytes/supplements etc

- Equipment and clothing choices, suits, helmet, shoes, goggles etc - (currently have a 2015ish focus road bike w carbon forks + cleats, are aero bars worth it?)

- Rules a novice like me should focus on and endeavour to comply to, common mistakes etc

Thank you all in advance your advice is much appreciated.