Congrats on your first independent change!
My permanent colostomy, due to rectal cancer, was last February. I change my wafer when it begins to digenerate, usually about a week, sometimes as much as 10 days. Wear time seems to be very individual for each of us.
I'm able to remove the wafer before my shower and allow my skin to breathe for awhile on change day, but this is because I can predict when my stoma will be inactive. With the flow frequency of your illeo, you may not have that option.
Sounds like you are doing great for one week post op! Read all the online ostomy discussion forums, keep asking questions, and you'll adjust to this lifestyle just fine. Attitude is everything.
Martha