Here is the different tenses. These seem correct.<br/><br/>(1)When will I do it if I don't do it now?<br/><br/>(2)When would I have done it if I hadn't done it then?<br/><br/>Is this possible? When would you use this?<br/>When would I do it if I didn't do it now?<br/><br/>Some say to use <br/><br/>When would I do it if I don't do it now.<br/><br/>but if so you might as well use (1)