It shouldn't be a defined amount of time and should be when you can. You should be able to constantly be learning about Bitcoin and cryptocurrencies in general. Researching could just mean looking at this forum and taking in the knowledge of other posters here.
I agree day by day is still a new learning to everyone. Way back then, i just started learning bitcoin through research also everytime I have free time. We can get knew knowledge by reading other answers here in forum. Actually researching was just one way of getting information about bitcoin. Spend your time to important things so that it wont be useless.