Sweet potatoes like it HOT. If you plant slips and it is not hot enough, they lay there and just sulk and then mostly will die or do so poorly that they waste space. Let's put it this way:
If sweet potatoes were people they would love August here in Texas. SP's like 90F weather, but LOVE 100F weather even more.

Here is a link, excellent information about the heat and how to know how much heat you have, for growing SP's:
https://www.sandhillpreservation.com/sw ... nformation

I don't plant mine until the first week of May, about two weeks after the tomatoes and peppers go in. Last year they were planted on May 3. Consistent daytime temps were mid 80's with lows mid 60's.

I used to start the slips by putting the lower half of a sweet potato in a jar of water but then I saw a Deep South Homestead video about starting them in soil. That made better slips for me and faster too. I love this guy's videos.

Growing healthy sweet potato slips:

Sweet Potatoes, a step-by-step planting guide: