The rent number in a BRRRR model means nothing without a lease-up line for the gap after rehab

Take a small three bed in a working class pocket, bought at 132k, 38k in rehab, planned rent 1,650. The refinance math works on paper and most of the cash comes back out, so on the spreadsheet it reads as a clean deal. What a lot of models miss is the gap between finishing rehab and signing a lease. Say the rehab wraps in early November and a lease doesn't get signed until the second week of January. Nine weeks of nothing coming in, a bridge loan still charging every month, utilities kept on for showings, and a heating bill on an empty house through a cold December. That can run about 5,900 in real money that never shows up anywhere in a model that jumps straight from rehab done to rent starts. The predictable part is that nobody moves between Thanksgiving and New Year unless forced to. A contractor flagging a two week slip is a signal to move the lease-up assumption, not to nod past it. The deal can still stand and rent fine afterward, but a first year's cash flow gets wiped out by a gap that costs nothing to model correctly. A sixty day lease-up line by default, and back-scheduling the rehab finish so the property hits the market in spring or late summer rather than December, closes most of that gap. A November finish is usually better slowed to a March finish than run through the holidays.