I have not seen anyone try DCA with altcoins, and I do not know whether it was a successful strategy or not.
1000 dollars is a good amount for a beginner. If you could do DCA with Bitcoin, it would be better. Stellar has not reacted well in the past years, so what is the reason for you to invest in it?
DCA with altcoins is very risky even they are top altcoins because top altcoins can be dead too.
Don't buy altcoins because they are top altcoinsDCA is best for Bitcoin in cryptocurrency market and I think it is good for Ethereum, the second biggest cryptocurrency too. With SOL, XLM, risk is high even with DCA strategy.
From that list, Bitcoin and Ethereum are the only ones that have maintained their position, and almost all alternative currencies have seen periods of peaks and troughs, and since DCA is a long-term strategy, I do not think it will be successful except with Bitcoin and Ethereum.
The amounts he wants to buy are not large, but it is a risk if cryptocurrencies are his only investment.