Should I get approved for lending first?

[Thomas Larsen]

I am working on my first brrrr property and its owner carry until I finish rehab. The rehab might take +3month. Should I get preapproved just to make sure I can get lending? If it takes longer i will have to get approved again because of the 120 days it is valid. This will be my first actual property let alone brrrr. Brandon Turner's book advises this but not sure because my credentials are pretty solid. 3+ years at same job. 755 credit. 140k income. 46k debt (truck and fifth wheel I live in)