Spring moves go smoothly or badly depending almost entirely on sequencing. The constraint most families are working around is the school year, which means the target is closing early enough in the summer to unpack and enroll before term starts.
Working backwards from a mid-summer move, that means financing sorted in early spring, offers going in through late spring, and a closing period of roughly four to six weeks after a contract is accepted. Build in slack. Appraisals get scheduled around the appraiser calendar, not yours, and repair negotiations after an inspection can add a week on their own.
A few things routinely break the timeline. Changing jobs mid-process, even for a better job, means the income has to be re-verified. Large unexplained deposits require documentation. Opening a new credit account before closing can change the debt-to-income ratio the approval was based on. None of these are fatal, but each one costs days you may not have.
The point of starting early is that by the time you find the house in May, the financing question is already settled and you are only negotiating on the house.