The approch you have outlined looks conservative to me. I have no expertise in steps, but that is how I would do a foundation. Your church is fortunate to have you available, but remember, next time they pass the collection plate, don't put your business card in, its cheaper to pay cash (humor). You certainly have your work cut out for you to finish by Easter Sunday.
I realize this is short on concrete advise, but I'm sure one of the concrete guys will pitch in their critique shortly. Meanwhile, a pat on the back for your gift of skill and time. Best of luck.