I’m with waterboy. Finance the money at purchase you get the best of all worlds, rates and protection (unlikely you’ll need recourse protection but it is better to have than not).
You can always submit the offer with no financing contingency so if everything blows up on the finance side you still close the deal all cash. That would be an extremely strong offer and you get everything you want right up front.
I’d check with a broker on seasoning, some guidelines say that you have to be on title for 12 months before before allowing cash out. Another factor to consider if you are trying the refinance later route.