If you are guaranteed of discretionary income, there's no need for you to build an emergency funds first; you can start your investment right away. Then after you have spent 1-2 months accumulating Bitcoin, you can start building your emergency funds gradually so if you have any emergency, you can freely sort it out.
I disagree with investing in bitcoin for 2 months before considering building your emergency fund, what's wrong with doing the two things side by side, it's obvious that that an investor can invest in bitcoin and build his emergency fund at the same time, this way you are not putting all of your eggs in one basket, so while delaying your investment until after building an emergency fund is wrong, deciding to delay building your emergency fund is also not an advisable course of action.
If someone buys Bitcoin with a loan, it means that he does not have an emergency fund and reserve fund. If he buys it when the price is lower than expected and later sees the price of Bitcoin falling further, then he will be in a very bad state mentally and if at that time his income source is closed, then first of all he will not be able to buy Bitcoin anymore and will have more difficulty in meeting his daily expenses. At that time, if he has a loan and has to pay only the monthly installments, he will be in a completely devastated state and will be forced to sell Bitcoin at a lower price than expected.
That's not the purpose of a loan in bitcoin investment, taking a loan doesn't necessarily mean the person doesn't have an emergency fund, loans are a way of taking advantage of business opportunities, in bitcoin investment it can serve as a means of securing more bitcoin in relatively shorter time, you shouldn't be planning on paying on paying your loan with your profit from your bitcoin investment, you should have an external income source that will cover your loan for you.