I'm a roofer with little work these days. A friend of a friend suggested if I would reroof his house, which is presently up for sale, he would pay me 1 1/2times my normal rate for the job when the house sold or six months from now whichever happens first. He's willing to put this in writing. My problem is he live about fifty miles away, how will I know if he sells his house. I thought of having him give me a check for the amount owed without a date, once the house is sold I would fill in the date and submit the check to my bank. Is this a legal option? Does anyone have any ideas or suggestions?