I don't really think that buying a fix amount of Bitcoin when talking about DCA is proper because to my own understanding, if you really want to buy through the DCA method, then you have to buy with a fix amount of money, weekly or monthly irrespective of the current price of Bitcoin, but if you want to buy a fix amount of Bitcoin, them you might spend more or less depending on the current price of Bitcoin, but the major challenge with this strategy is that you will be forced to tamper with you emergency fund that would have been for your upkeep till month ending when you are expecting money from another source.
The truth is that is actually very difficult and challenging to constantly buy a certain amount of Bitcoin on a weekly or monthly basis through DCA method reason been that the price of Bitcoin use to be very volatile and the possibility of meeting or buying at the same price as the previous week is not certain and perhaps it could be that the price has gone up way beyond the price of your last buy so perhaps that's were the ability to adjust to Bitcoin accumulation pattern comes in, so perhaps you can still accumulate with your normal weekly budget even if the amount of Bitcoin you will have will not be up to the last accumulation but however if you have other spare funds that doesn't have any budget for, then you can adjust the accumulation pattern a bit.
, before an investor will have this decision definitely he must have got all his plan worked out by making provisions for his personal needs emergency and reserve fund and also have factored in the price fluctuations as a principle factor of Bitcoin functionality. I think this whole thing is apparently and typically based on individual financial capability.