first AKC agility trial in three weeks with our 3 year old border collie aussie mix and the gap between "she runs the practice course clean at 32 seconds" and "what an actual trial is going to be like" is suddenly a lot wider than i thought and i need real owner perspective from people who have been on the other side of that first trial

Marlowe is our 3 year old border collie aussie mix, 42lb, female, we got her from a rescue at 4 months and started agility foundations at 14 months with a CPDT trainer who runs a small agility club out of her property in central new hampshire. we have been training seriously for the last 18 months, 2 group classes a week plus practice sessions in our backyard with a foundation set of 6 jumps, a tunnel, weave poles, and a table. she is the smartest dog ive ever lived with and she loves the work in a way that has changed how i think about what dogs find rewarding.

where we are. she runs the practice course at our trainers field clean (no faults, no off-courses) at roughly 32 seconds for a standard 14 obstacle course. her weaves are reliable at 12 poles. her contacts (a-frame and dogwalk) are 2 on 2 off and she stops every time at practice. start line stays are solid. she will work at distance to about 18 feet from me which our trainer says is enough to start in novice. her drive is high without being frantic. she reads my body language well. she has been doing fun matches (informal practice trials) at our club every few weeks since february and has run those clean.

her first AKC trial is in three weeks at a venue 90 minutes from us, two days, four runs total across standard and jumpers. our trainer has been pushing us toward this date for two months and Marlowe is ready by her assessment. i am the variable now, not the dog. she has been telling me for the last three weeks that the dog is fine and i am the one who needs to get my head right and i am increasingly sure she is correct but i do not know what i do not know about the trial environment vs the practice environment.

what i think i am asking. one, for people who have run their first trial with their first agility dog (especially a high drive border collie or aussie type), what was the gap between practice performance and trial performance, and what specifically caused the gap (handler nerves, dog overarousal in a new environment, weird footing, the gating system, the scribe table activity, something else). two, what are the trial-environment-specific things that are not really practiced in a class setting that i should be preparing for in the next three weeks (crating in the venue, warmup ring access, the actual walk through, the timing of runs, how long the day actually is, how the dog handles a 6 hour day at a trial). three, what are the rookie handler mistakes you actually made at your first trial and what would you tell yourself the night before. four, our trainer is going as our coach for the weekend which is a huge benefit, but for those of you who went without coaching, what survival tools did you use. five, for the high drive crossover dogs (border collies, aussies, mixes of both) what specific overarousal mitigations actually worked in the gating area and the walk to the start line, because we have a small dose of this at fun matches and the actual trial is going to be a different intensity.

not asking about whether to do it. we are doing it. asking about what to expect and how to be a less embarrassing handler on the day. Marlowe has earned this and i want to not be the weak link