The strongest case for a small first deposit has nothing to do with markets. It's that you're testing a process — sign-up, verification, funding, a first position, and crucially, a withdrawal — and that test should cost as little as possible.
Run the whole loop with the minimum deposit. Fund the account, wait, withdraw part of it, and see how long the money takes to return and whether it comes back to your original method. A platform that handles a small withdrawal cleanly is one worth trusting with more.
Only after that round trip does it make sense to think about size, and even then gradually rather than all at once. A bigger deposit doesn't make a strategy work better — it simply makes the same outcome larger in either direction.
Why the first deposit matters most
The first deposit sets the tone. An amount chosen because it's comfortable tends to lead to calm decisions later; an amount chosen because it felt like the maximum possible tends to lead to decisions made under pressure.
A sensible starting point
Money you wouldn't need back within a year, in an amount whose loss would be annoying rather than damaging. That's a personal figure only you can set.
Adding to it later
Topping up a balance you already understand puts you in a far better position than starting large and learning the hard way.
Questions worth asking before you commit
How do withdrawals work, and where do they go? What gets deducted, and by whom? Who do you contact if something looks wrong? A platform that answers all three clearly, in writing, is behaving the way it should.
Investing involves risk, including the possible loss of some or all of the capital you invest. The value of investments can fall as well as rise, and you may get back less than you originally put in. Do not invest money you cannot afford to lose.