Of a truth waiting to get all our budget figured out before getting started will make us not to start our accumulating journey on time, but I feel that this is supposed to be a personal decision if we are to get started or to wait until we get all this figured out. so you can't possibly say that is not necessary to wait until we get all this matters sorted out before getting started, as you can't speak for others, If you feel that getting started is your best step to take maybe with time you will be looking for a way to get all this matters figured out, is also a nice idea. So I feel that this is just a personal decision.
It is a waste of time when you try to set budget since the goal is prolly 4, 5, years and more investing period. If you have a goal/target that is more than enough to stay in line with your investment. Imagine, making a budget o $5000 in total as your capital, with time it may change if the price of Bitcoin gets higher or reduce. That amount could get you lesser or higher fractions of Bitcoin. I think the best approach is to have in mind how long we want to invest and what amount of Bitcoin we would love to have in our portfolio.
Investing into Bitcoin with a budget in mind wouldn’t be quite easy, Bitcoin is a very volatile assets so it wouldn’t be very easy to have an amount in mind to use in investing, that is why I think it’s more reasonable to accumulate gradually on a weekly or monthly basis depending on when you’ve have a discretionary funds, and planning on budgeting will definitely make us not to accumulate much bitcoin considering the volatile nature of bitcoin , because there are times when Bitcoin would increase and times when Bitcoin would decrease, having budget in mind would probably make us not to exceed our budget, Waiting to get whatever amount of budget set aside before starting to invest would be a waste of time because you might not get that budget which you planned.