A long-term investment of 4 years to 15 years or more, an investor is not boarded about how the market goes either up or down,all he his focused on is how to buy more Bitcoin into his portfolio that will be beneficial to him in future .
You don't really have to wait for the dip before you invest more, just keep buying and accumulating in respective of how much Bitcoin is, and when the dip comes ,it gives you the opportunity to buy more and aggressively if you have reasonable amount of cash with you, it is not adviceable to wait for the dip, continuous investment is the best and the wright thing to do.
Though I think it depends on the amount of bitcoin you wish to accumulate and also the amount you're investing with,
but i still wonder what will be holding an investor from not reaching the status of overaccumulation before this 15 years. However, i think the idea of buying bitcoin aggressively when you have already reached the status of overaccumulation does not make much sense to me, if i get to the status of overaccumulation i will take it very slowly, i can decide to buy every dip since i have build a very large portfolio. is only those no coiners/ low coiners that is advised to invest in bitcoin without paying any attention to the market fluctuation by using the DcA method, as a no coiner/low coiner and you're hoping to buy every dip definitely it will take some couple of years before you can be able to reach your target. But when you're using the DcA method you won't even consider the market value before investing, and this is going to make the accumulating process keep moving instead of waiting for the market to dip before investing.
You have to remember that even a guy who puts 10% of his salary into bitcoin, it will take him 10 years to reach 1 year of his salary invested into bitcoin. I consider 10% reasonable if your discretionary income can tolerate it.
There are folks who are investing into bitcoin at much more whimpily than 10% per year.. so it is going to take them a while to reach over-accumulation status, perhaps even more than 20 years.
Of course, bitcoin price performance can help them, but if they were only investing 1% of their salary into bitcoin, it would take them 100 years to get 1 years salary invested into bitcoin... so it can be questionable if some whimpy levels of investing are going to be enough to get to overaccumulation status. Of course, any investment into bitcoin is better than nothing, but it pays to have a bit of an ability to increase our investing aggressiveness, especially for any of us wanting to reach overaccumulation status.