well, looking at the plan, it was a good plan. However, what is planned is sometimes easier than the reality. This plan will truly be felt when he does this continuously and sticks to the principles of the plan he makes.
However, many people fail because of FUD, or seeing the price of bitcoin fall, so they rush to sell the assets they have accumulated. However, I have a suggestion, if you want to do this in the long term, then don't even think about the price of bitcoin when things are bad and stay focused on your planned asset savings. When market conditions improve, or even rise, you can think about the next steps regarding your plan.
Have good planning for accumulating few percent of passive income to invest in bitcoin but in the reality we face many choose make us consistent or not keep investing in bitcoin every months. FUD and bad news sharing every time make us little doubt for consistency investing or accumulating in bitcoin every month but OP have good decision keep spent his fund $50 every month for investing in Bitcoin. Actually holder or investor is the winner at the end and OP have try to fight with how many FUD sharing every day and keep consistency for accumulating $50 every month to earn much profitable in the future when Bitcoin success raise to higher price. Need strong faith for long term profitable in bitcoin actually with small capital use for investing.