Hiragana can take anywhere from a few days to a few weeks, depending on the person. The advice I like to give beginners is to learn Hiragana in sets of 5 (as they appear in the chart). So, one set would be [あ, い, う, え, お], another [か, き, く, け, こ], etc.
Once you get comfortable with one set, you move on to the next. How long that takes is up to you. You could do 2 sets a day, or 1 set every two days. Doesn't really matter how long it takes, as long as you learn them well.
TLDR: It's up to you. No need to rush.
PS: When I say "depending on the person", I'm mostly referring to time and effort, not ability. I think almost anyone can learn them in a few days, assuming they had the time and really wanted to. Not including adequate writing ability, that would take longer.
