Question about VA employment

I’m hoping some current/former federal employees or HR folks can give me some perspective because I’m probably overthinking this.
I recently applied for a GS-7 position for the VA in the social work department.

For some background, I’m a veteran with 5 years and 2 months of honorable Marine Corps service, a bachelor’s degree, nearly 3 years of experience working directly in veteran housing/SSVF, and about 3 years of experience serving Veterans through a VA Vet Center. The position is closely related to the work I’ve already been doing.

I interviewed for the position and apparently did well. The hiring process moved extremely quickly. I received a tentative job offer and have been going through the VA onboarding process. The hiring supervisor has already emailed me that my paperwork was submitted and that she’d let me know if there were any updates.

I’m now completing the OF-306 and ran into Question 12, which asks whether during the last 5 years you’ve been fired from any job, quit after being told you’d be fired, left by mutual agreement because of specific problems, etc.

Unfortunately, I do have one thing that applies.
In 2022, I worked part-time as a sales associate at a private-sector company and was terminated due to performance issues. I was also a full-time student at the time and was balancing multiple jobs/responsibilities. It wasn’t anything criminal, dishonest, or misconduct-related. It was simply a part-time job that didn’t work out.

I initially really didn’t want to disclose it because I was terrified that the VA would rescind my offer. But I ultimately decided that lying on a federal form would be much worse, so I answered Yes and explained that the employment ended due to performance concerns while I was a full-time student balancing multiple jobs and competing responsibilities.

Now I’m freaking myself out wondering if I just screwed myself after getting this far.
My bigger concern is timing. I currently have a job that I’m still working, and I obviously don’t want to give my employer notice until I’m reasonably confident the VA job is actually happening. At the same time, I don’t want to wait too long and screw up my transition or give my current employer less notice than I’d like to.

I don’t want to give my current employer two weeks’ notice, have them start planning around my departure, and then have the VA unexpectedly rescind the offer because of something on my OF-306 — leaving me without either job.
For people familiar with federal hiring:
At what point would you personally feel comfortable giving notice to your current employer?

Would you wait until the final offer and confirmed start date, rather than doing it after the tentative offer/onboarding stage?

And regarding the OF-306: Has anyone disclosed a previous private-sector termination for ordinary performance issues several years earlier and still received their final federal offer?
I’m not looking for reassurance just for the sake of reassurance — I’d genuinely like to know how federal HR/suitability tends to look at something like this.

My understanding is that the bigger issue would be lying or omitting the termination rather than the fact that I was fired from a normal private-sector job four years ago. But I’m nervous because this is my first federal position and I really don’t want to lose the offer over something that happened in 2022.
Would you be concerned in my situation, and when would you consider it safe to give notice?