Is my repair credit plan ok?

So I have about 5k in debt. I was planning on paying all off by September of this year. My grandpa left me over 25k in his will and in less than a month we have the final hearing for the probate court. Then everything will be distributed. I plan to pay all the collection agencies within the same week. Then in september get a secured credit card or secured loan. I know ppl say I should keep a line of credit open, does my car that im financing and the secured credit car count? Will paying off all my debt in one week cause a problem?