I was to start my Methylprednisolone 4 mg pack I took day 6 pill & 1 of day 5 by mistake?

Let´s see if I get it:

You took on your first day 6 pills and you were supposed to take only one, so you took 24 mgs. instead of taking 4mgs., that is 20mgs. more that you must not have taken, I suggest you call the Poison Help line at 1-800-222-1222, and tell them if there is any sign of intoxication.

What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

An overdose of methylprednisolone is not expected to produce life threatening symptoms. However, long term use of high steroid doses can lead to symptoms such as thinning skin, easy bruising, changes in the shape or location of body fat (especially in your face, neck, back, and waist), increased acne or facial hair, menstrual problems, impotence, or loss of interest in sex.