In the ninety days immediately before the second anniversary of the date they became conditional residents. If jobs remain unfilled, the petition may still be approved on evidence that they will be created within a reasonable time under a credible plan.
The window is fixed; the job count has some give
The two-year period starts on the date of admission as a conditional resident, printed on the permanent resident card, not on the date of the investment or of the petition approval. The I-829 must be filed within the ninety days before the second anniversary; a petition filed before the window opens is rejected and one filed after the anniversary terminates conditional residence unless USCIS accepts a showing of good cause. The receipt notice extends residence while the petition is pending, and adjudication can take a long time, during which the family may travel with the receipt and the expired card.
On the jobs, the regulation and USCIS policy allow removal of conditions where the ten positions were not all created by the filing date but can be expected within a reasonable time, and USCIS reads that against the business plan and the progress made. In the hypothetical, eight employees on payroll with two positions posted and a documented seasonal ramp is a credible showing; two employees and no hiring record is not. Keep the hiring schedule current and hire ahead of the deadline where cash flow permits.