Starting Bitcoin investment with little capital will be very challenging mostly if that happens to be the major survival option of the investor. And in cases where the investor plans on using the proceed to solve their needs they might end up selling when the price have dropped just to settle the pressing need of that time.
As experienced investors are there measures that can be imbibed by new investors with little capital to help boast their capital. Some will want to mention patience which I will agree to but in situations where the money is needed to meet an emergency need how to you tackle such situations. Your formula might be a saving approach.
If money is that tight then you do not have anything to rely on other than your luck and hope that things go well while you are invested in bitcoin and its price is low, it is not the most reassuring answer but it is an honest one, as most investors will keep an emergency fund of a few months of their salary to avoid touching their assets during those difficult times, but if your capital is that low then it is unlikely you will be able to do this.