Actually, a steady income is a MUST for saving a part of your salary in Bitcoin, especially if you employ a DCA sort of strategy. Because it doesn't matter what you call "prepared", if you don't have a steady income then you definitely ARE NOT ready.
I think you meant source not a steady income. I believe you can't invest what you don't have
As long as you have a source, whether steady or not there's room for investment.
I take my DCA as me paying for my monthly subscription.
There are times that funds at hand are extra I increase it while times lower I reduce it.
You just have to be smart about it.