Financial talk

Ok, so I have $6,000 in my stock account and I am taking on a Margin that will give me extra buying power. Now, I am aware that I am able to trade 3 times during a 5 day period. With all this being said, here is my question: Lets just say that it is a Monday and I put my $6,000 into a stock that ends up giving me a retun of $200. Lets just say that I sell that stock on Wednesday and now have a grand total of $6,200 BUT it's still Wednesday and my money hasn't been processed back into my account.. but now worries, because I have my Margin money. Can I then put $6,000 of that margin money back into that stock even though my other money is still being processed and everything will be ok?? I think I have this all figured out but I just want to double check that it's correct, just so I'm as prepared as I can be. THANK YOU!:)