Plan the cash, not just the payment
What goes into it
Start with the price and your down payment. What is left is the loan. The fees and any points are worked out as a share of that loan, not of the price. Prepaid tax, insurance and the first escrow deposit go in as their own dollar amount, because they depend on your closing date rather than your loan.
Why no single percentage fits
What you pay for the appraisal, the title check, recording and transfer tax depends on your lender and your state. Prepaid bills shift with the day you close. A rough percentage is only useful before you have real numbers.
Points only pay off over time
One point costs 1% of the loan and buys a slightly lower rate. How much lower is not fixed. Divide what the point costs by what it saves each month, and you get the number of months before you break even. Sell or refinance before then and you lose money on it.
Swap estimates for real documents
Use the Loan Estimate to compare lenders and the Closing Disclosure for the final numbers. Seller credits, lender credits and the deposit you already put down all change what you actually hand over.