DCA not require amy specific exchange or any introduction you just follow the DCA strategy and set the target for every weeks or month. and always invest such amount of money which amount you afford to hold for long term. then you will be success in the holding amd DCA will minimize your risk of investment
Investors actually need exchanges to purchase bitcoins because other options like Person to Person trade is risky without Escrow. You will have safer purchasing experience when buying on a centralized exchanges if you are not familiar with Peer-to-Peer trade.
DCA in theory can be applied with scheduled regular purchases like daily, weekly, monthly or quarterly but if you can not afford your capital to do regular purchase, you can simply accumulate bitcoin when you have free capital.
However, investing for a long time and trading aren't the same. So for those we are trading, we do not often follow the DCA.
Investing and trading are different and people must store their fund for trading and for investing in different accounts, wallets. If they store two capitals for investing and trading in a same account, they will not control their activities well and no longer be able to be investor, but change to be a trader.
No doubt, DCA is the best way to build our portfolio. We can get a high return once a year if we can hold it for a long time.
With DCA, we spend little of our money to purchase bitcoin each time but with time, after a while like one year, two years, we will be shocked when look at our portfolio and see how much money we already spent for our Bitcoin investment.