start-up finances
You have 10 million AS$ to start with. Depending on the market situation and the expected earnings, you should keep a reserve to be able to pay salaries and leasing rates.
cash flow and how much to spend
Salaries will be deducted at the weekday and time you first created that particular airline, same for leasing rates but based on the time of delivery of the particular aircraft. You can find all upcoming payments in the cash flow statement.
Since the first payments won't be for another week, you can spend a lot of your money. Since the leasing costs and security deposits for leased aircrafts are at a fixed rate, you can make a rough estimation on how much money you can spend at the beginning.
You have 10 million, if you use 9 million (don't forget that you will have to pay for installing the seats and maybe for training pilots, so that is part of the 9 million), the maximum leasing rates due after the first week will be euqal to (in case of pure cargo operations - nothing to start playing with) or less than 900,000 $ (that is, because security deposit is always 10 times the weekly leasing rate. the security deposite, by the way, will always be 1 / 20 of the book value of the a/c).
So, max 900k $ for leasing rates plus staff salary. 1 million will cover most of that, so you should be fine spending 9 millions assuming you will make at least a tiny small profit in your first week. If you chose a good location, that will not be a problem at all.
If you are unsure, keep more money as a reserve, but in aviation, only money in the air generates more money.