The most important thing is to start consistently, not the amount of Bitcoin. To start any investment, you should first have money, sufficient knowledge, or absolutely perfect market conditions.
Whether you are a pensioner, a student, a low-wage earner, or someone who has something in hand at the end of the month you can still be a successful investor in the world of Bitcoin—if you are consistent.
For those who have a long-term view of Bitcoin investments, the main objective should be to hold on to time. Whether big or small, this is your real capital. You need to see each day, each week, or each month as an opportunity—not in the light of market momentum or news. Small steps make a big difference in the long run.
Money is necessary before starting but when looking at it from a different point of view whereby having a source or sufficient money before investing can be difficult for starting bitcoin investment rather when having a discretionary income meant for investing sounds better for example having money is different from a discretionary income basically this fund is needed for investing in bitcoin. Sufficient knowledge might not be the major criteria instead learning the basic knowledge about bitcoin can be helpful at an early journey afterwards an investor can decide to go deeper obviously bitcoin knowledge can be a bit broad.
If a person condition is that low as mentioned they can buy bitcoin in little fraction according to their discretionary income and hold for a long time, the dca strategy is mostly common in this field, create a budget after monthly or weekly pay dividing each share according to the demand while bitcoin investment is at the corner, after listing down every needs the (discretionary funds) left over funds is meant for buying bitcoin and building the emergency funds.