I got the kit, van Ionic system etc etc before I had a single customer, so I appreciate where your coming from. Get the part time job and then leaflet and canvass the rest of the time.
Probably the biggest issue you will have is feeling like giving up. Fight through these times. It will happen when you have had a run of bad luck, people messing you about and perhaps something going wrong with the van/system.
The funny thing is, when you have got through the bad time, something good/positive will happen alomost as a reward for not quitting.
It's like getting a big ball to start rolling, very hard at first but once it's going things are much easier. Do the best job you can every time and you will get there.