If the investor fears that his investment may be irregular, then the investor can form an emergency fund if he wants.
If an investor creates an emergency fund, if they do not have enough money to invest in any given month, they can use the money from that emergency fund but still continue to invest in Bitcoin.
An emergency funds is compulsory for a long-term bitcoin investor to succeed in his bitcoin investment because it will save you from selling your bitcoin prematurely when you are hit with real life emergency. If you don't have an emergency funds, it means that you are gambling and not investing because you didn't provide a means of backup for your bitcoin investment.
When you are hit with real life emergency and you don't have an emergency funds, you will sell your bitcoin at loss if bitcoin price is below your entry point. Selling part of your bitcoin investment isn't a good way to pile up your bitcoin for proper growth overtime. This is why as a new bitcoin investor, you should start your bitcoin investment the moment you have your discretionary income.
If you don't have any emergency funds available when you are about to start investing, you should share your discretionary income to two parts and use one part to for your weekly DCA and the other part for building up your emergency funds simultaneously with your bitcoin investment until your emergency funds is at least three months of your expenses.
If you don't have your discretionary income to invest in bitcoin and you are not sure of when it will be available, it's better that you don't use your emergency funds to invest in bitcoin but hodli to your bitcoin and buy whenever your discretionary income is available.