You can't rely on others when it comes to this lifestyle change. You have to do it on your own. I'm glad to see you aren't letting a flaky workout partner get you down!
I've had so many people flake out on me that I don't even try to have a workout partner anymore. I find I prefer to work out either in my group fitness classes or on my own.
I understand how you feel about your partner being late. I'm a punctual person and it drives me CRAZY when people are late! So I'll just start without people or leave without them, etc. I've gone to restaurants and had people arrive a half hour late or more...so I'll sit down and order and say to them "so glad you could join us for the meal!

" when they arrive. I'm evil like that. I'd probably say something sarcastically like that to a person who was chronically late to workouts too
Hey, your time is valuable!