Couch to 5K

Just finished week 4 day 3 of my Couch to 5K program. I'm running on my treadmill. I'm hoping the shoes I ordered last week come today or tomorrow. I had 3- 3 minute walks  and 2-5 minute runs.  I don't really run, only jog at 3mph.  I don't want to injure myself. When I'm finished with the 8 week program, I'm hoping the weather will be nicer here (translated- no rain and temps higher than 60) so that I can move outdoors. I have a bit of osteoarthritis in my knees.  I hope that I'm not doing any more damage to them.