If you are investing into bitcoin with your excess cash (if there is such a thing?), then you should realize that you are continuing to build your BTC stash, whether you are able to invest $100 per week or you can only invest $10 per week, and I would imagine that after the first 4 years of investing into BTC at whatever was your rate, you are going to be in a better position to decide what to do next and you should be in a better position to assess whether your ongoing investment into bitcoin had put you into a better position than if you either had not invested into bitcoin at all, or if you had chosen some other investment or if you had chosen not to invest.  These are not easy questions to answer unless you have acquired enough confidence that bitcoin is amongst the best of investment avenues that are currently widely available to all people around the world... but even the fact that bitcoin is likely amongst the best of current investments, we still are NOT guaranteed that we are going to be better off to have had invested into it rather than investing into something else or just consuming our investment amount.

Once you get over the hurdle of deciding upon bitcoin and then focusing on carrying out your BTC investment/accumulation/buying plan, you won't be able to change what you did 4-10 years or longer down the road, even though you are able to change at any time along the way, if you change your mind about the plan that you create  and/or follow today.

Of course, ongoingly you will be faced with choices regarding how regular and aggressive (or whimpy) you should be in your investment and the extent to which that you might want to tweak your plan along the way.. so the level of your aggressiveness(whimpinees) and consistency in carrying out your plan can end up having pretty decently sized compounding effects down the road, whether you are looking at 4-10 years or maybe even some longer timeline in which you may well end up getting to a wealth accumulation location that you had not thought that you were going to be able to reach based on your personal circumstances and the ways of the world.  And sometimes investors can become too greedy and too aggressive in their investment approach - so there is a balance in which being too aggressive could end up working against you too, even if you might consider that being aggressive might be a good thing... there are ongoing needs not to overdo what you are doing in such a way that you end up taking way more risks than necessary.