For example, let us suppose bitcoin prices start to pump for the next 7 days, so if OP buys daily he will get more satoshi's as compared to if he bought all in on the seventh day when prices are high. In this case, the saving fee may not be that important.
And if the price starts to dump for the next 7 days, then the reverse is true and OP would have ended up with more bitcoin if he bought all in on the seventh day than if he bought in daily.
As I said above, the more frequent your buys then the closer you will come to buying in at the average value of bitcoin during the period of time in which you are buying. Whether this works out as more or less profitable than buying less frequently depends entirely on what the market does during that time. But again, the whole point of DCA is not to maximize profit, but to minimize risk, and the close you come to buying at the average price then the smaller your risk becomes.