In short, with the exception of adding a fairly meager sum to your total available credit, I don't think the J.C. Penney card adds very much to your credit profile. I believe it would have to be a hard pull on your credit. The prequal is generated from a soft pull, but approval of any extension of credit typically requires a hard pull. You should also be careful not to generate too many frivolous inquiries. That can scare lenders off as you can begin to appear "desperate" for credit.
I'd also add that, imho, if you don't shop at a place religiously, dump the store card. I only keep my Amazon Prime Store Card because I buy tons of stuff from Amazon and use the promotional financing. In my opinion, if you only shop at places occasionally, store cards aren't really worth it. The fact you have the Amazon Visa and the Amazon Prime Store Card is redundant. I'd choose one to keep based on your needs (cash back or promotional financing) and dump the other one. I'm only suggesting closing cards because you mentioned they were all opened this year, so - barring any damage already done by the hard pulls - it should have minimal effect on your FICO scores.
The biggest thing is to reduce your utilization and keep it low. Forty percent certainly isn't the worst, but it's a decent chunk of change given your available credit and ideally it would be half that or less. If you can pull that off, I think you're in a good place to garden for a little bit. Let things go for a year and watch your scores go up!
