I agree with your strategic concept that investing is very good if it can last up to 3-4 years, as we have seen from year to year with significantly increasing prices. there is nothing wrong if you can invest now and can save up to 4 years in the future., because it is very likely that bitcoin will reach $300k in 2025 in the future.
If that's the goal for investing in bitcoin. Make sure that you won't be selling at $100k-$200k.
Because if those prices have come, you'll be tempted to sell at those prices. Even I, I wouldn't have any thought of selling some by that time.
Each and every holder have different approach to invest and bitcoin like for some DCA would be beneficial but for this you need to have regular flow of income so that you can put up money at your desired intervals but on other side if you can't do that and want to put some extra funds at once you can opt that strategy also and can do that whenever you wish to to so.
But then we say about holding then it's also dependant on how much years we can be patient enough to hold or sometimes we are in emergency so need to cash out our coins so it's not at all problems because we save to use them whenever we are in need.Suppose you have invested at $50k then prices are $100k now after 2-3 years then selling at this level already put you in the profitable situation so selling at that time won't be loss but if can hold even further then it's fine but use your mind as profit is main point if we take it as an asset class.So it all varies and we can't say when to sell or buy as timing out market perfectly is very hard to achieve.So take and manage your investment in best possible way you can.