I agree with the posters. Start slow and small. I started out with lots of phone shops from Intellishop. It took me awhile to be able to do 3 physical shops in one day. I remember the first time I did it, I was sure that I wasn't going to be able to do it all correctly. The key is to slow down until you learn more.
When I started I had an individual file folder for each shop. Then I would keep the file in case there were questions until I was paid. I wrote the key points on the front of the folder. Plus the payment amount and payment date. I'd print out all of the guidelines and read them 3 times. Once right before going in the shop. Now, I just text myself keywords and then I can look at my phone while on a shop to see if I covered everything. Most my shops I know by heart though.
November and, especially, December are really busy shopping months. I made over $1,200 both months last year. I am not sure what you are expecting to make to cover a full-time job but $1,000 a month is a lot of money in mystery shopping, you are VERY busy.
Nowadays, I wait out my favorite shops until they are highly bonused and just cherry pick jobs. Just don't put all your eggs in one basket by expecting all your money to come from mystery shopping. Try maybe merchandising 10-15 hours a week. You still have the flexibility of hours but you will get a regular paycheck. Just an idea. I just don't think that it is meant to be a full source of support. Especially, if in two months you've only gotten 3 jobs to pay you. This isn't a job for everyone.