No reliable timeline can be promised; the official process runs through fee, vetting, instructions, gift and then residence subject to visa availability. Before any payment, the employee should resolve her admissibility review, settle the sponsorship agreement and reread the official page.
Vetting and visa availability set the pace, not the employer
The official Gold Card page currently says the process should take weeks, but that estimate is not a guaranteed completion date, and an employer's enthusiasm does not shorten government vetting or create a visa number. The sequence is the applicant's submission and nonrefundable processing fee, USCIS instructions to submit Form I-140G and supporting documents, vetting, the gift after successful vetting when instructed, and then EB-1 or EB-2 permanent-residence processing when a visa is available. Hypothetical example: a Shannon software developer's employer wants her relocated by the end of the year and proposes to pay immediately; the sensible order is first a review of her own immigration history for admissibility issues, then a signed sponsorship agreement covering dependants and repayment, then tax advice on the arrangement, then a fresh reading of the official page, and only then payment.
Delays can come from any family member's vetting, from the classification chosen and from visa availability. Because the processing fee is nonrefundable, paying before those steps are complete converts an open question into a sunk cost.