Years, and the length depends on source-of-funds preparation, adjudication times and visa availability for the applicant's country of chargeability. It cannot be quoted as a fixed period.
Three separate clocks run at once
The first clock is the family's own: assembling the source-of-funds record, choosing and diligencing the project, and committing the capital. The second is adjudication, which varies and is outside the applicant's control. The third is visa availability by country of chargeability, published monthly in the bulletin, which can add or remove years independently of how well the file was prepared.
Because conditional residence lasts two years and is followed by a further petition showing the investment was sustained and the jobs created, the full arc extends well past the initial approval. Any plan that depends on a specific arrival date should be treated with suspicion, and family decisions about schooling and property should allow for a wide range.