Its better than no feed! But really, I don't think it will make too much difference. I would just get the other as soon as you can and mix the two. Medicated food has amprollium and its not like putting them on and off of an antibiotic.
They will be fine. I live over 10 miles from the nearest town and sometimes I have ran out and not wanted to go to town till the next day or something...I will just feed mine yogurt, cornbread crumbles, tomatoes, and dig them up some bugs. They are just fine.