Waiting and piling up the cash in fiat before you buy is totally the wrong approach if you ask me because Bitcoin isn't a stable coins and you can't expect the price to sit around and wait for you to gather all the money first before you now use when you are satisfied with the money for investment. The right thing to do is simply to keep striving to accumulate just like you have stated with the little earning so that you can meet up with atleast the lower price because you can't tell when the price might go up or even down.
Even though bitcoin is not a stable coin that shouldn't discourage who wants to save up money to invest from investing in a wrong time, note, as the price isn't stable it makes it easier for any investor to save and invest whenever he wants to as no time is late to invest and to take profit. I think it is right to have have a stable income before investing in bitcoin since it will reduce the panic and fear of the investor but anyone who is investing with a little earning will only be hoping to get a quick profit which may never happen easily unless the price increased tremendously after investing so I think saving enough money and having a good and stable income should be considered by anyone before holding bitcoin.
There is no room to fear as you said all one need is to planned well and save before engaging on the investment, this can help investor to accumulate even more as the attention to quickly withdraw won't be there is a result of not planing properly that make most people that engage on BTC begin to consider withdraw so fast because they are choke with other responsibilities that that can't deal without venturing or touching tje investment,you can only see the value more when there some set outside strategy of handling some daily impressing needs outside one investment.