I'd leave it blank. IIRC this thing is generally for if you have a 'fiscal year' that isn't the usual calendar year, and (presumably?) you don't. Everything on the 8854 looks to be qualified with "as of your expatriation date", so that not even the IRS could easily misconstrue anything here.

 

Yes, I'll do that, then.

I had seen an earlier thread suggesting that I should complete it, but it seemed like a somewhat counterintuitive interpretation of the form, given it's tailor made for this purpose - unlike the 1040 and 1040-NR, neither of which are particularly well-suited to edge cases like dual-status years.

https://expatforum.sitesdebloques.org/threads/8854-questions.1539503/

Thanks for your advice!