Why not start in the last week?
The last week fills with shopping, cooking and visits, and there is little time for washing upholstery, which needs complete drying. If you leave it late you may have to use sofas or carpets while damp, which adds odour and lengthens drying. Specialist team slots also shrink as the month approaches, so you may not find a time that suits you.
Spreading the work does not mean cleaning every day; two or three days a week with one clear task each is enough as long as the plan is written down and the family shares it.
