If your monthly income is stable it's quite easy to implement a DCA strategy to buy Bitcoin without worrying about the right time. The reason is that you always have sufficient capital so you no longer have time to worry about what happens to market conditions, whether they are rising or falling drastically.
I don't know why you're getting it twisted, you don't need a stable income before you can invest into bitcoin and DCA. What you need is your discretionary income and you are good to go. I have seen a lot of people who have stable income but still cannot meet up to their monthly needs how will such people invest.
Someone might win a lottery or a jackpot and decide to invest part of the the money into bitcoin by using DCA. He can invest $100 weekly and spread it over several weeks and keep his bitcoin investment ongoing overtime. Same applies to a contactor whose income isn't stable, the moment he get paid he can use his discretionary income and spread it in several weeks with DCA. Financial management is very important when investing in bitcoin
It will be much easier if you know your source of revenue. Having a structure plan will make it easier to realize its potential. The level of your spending determines whether or not you will have available a description income. Someone who earns a lot of money steadily may not be able to get discretionary income because his spending is not well controlled, whereas someone who earns a lot less may be able to manage and set aside money to invest, allowing you to protect your investment and maintain your ability to hold bitcoin. When faced with hardship, be cool and focused.