Since you have not done this in a while and you said you jacked it up last time I don't think you should fool with this. There are several reasons that I self relax: 1) I absolutely refuse to pay someone $60 or more to put a $5 or $6 relaxer in my head, and only on my new growth at that! These relaxer prices are highway robbery, pure and simple. I have never understood how they justify these prices. 2) I can't trust just anyone with this-which makes it hard for people like us who won't let just anyone near our heads, especially involving chemicals! 3) I'm comfortable being able to navigate around my head. I'm able to relax, color and roller set my own hair without any problems-and do it neatly. I also use Cream of Nature Mild Lye Relaxer.
Don't risk the condition of your hair, which I'm sure must be healthy! Try to find someone. If you do find a stylist go on a day where they are not so busy so you have their undivided attention! Do you have friend that you trust who could apply it for you and do it quickly so that you don't get overprocessed? I'm worried that since you have not done this in a while you may overprocess your new growth and/or overlap.