I'd go against any time-deposit schemes since one, if in case you have had an emergency situation and you can't get any cash immediately and two, you literally won't earn anything significant off of it, really, and it's better off allocating that 20% into your emergency fund or invest it into something else. I'd only take it to a cryptocurrency investment if I know I still have the means to spend once an emergency situation happens, or my expenses aren't that high and I have spare money to spend. But for minimum-wage earners, I suggest keeping it for emergency and just try to invest whenever you have something extra.