I have just got a second-hand Ibanez SR305EB.
Clearly, it'll take more than just 2 days to adapt to 5 strings -- 2 weeks? 2 months? I hope it's not 2 years (or never).
Especially tricky is when I have to use the G string -- it seems like a string too many.
It also seems easier to play fingerstyle than with a pick.
How long did it take you to adapt?
I switched to 5-string about 3 ish years ago.
My advice.
Yes, put your 4-string away. Play only the five.
You only have the one 5, hopefully you like the string spacing. You will find that not all 5's are created equally. Some have "very" narrow string spacing. 16/16.5mm Spacing. Some maybe less. Some are as wide as 19mm (some maybe more). You should play as many as you can until you find the spacing you like.
Scale. There is where things get really weird. I've seen 32-inch all the way to 37-inch scale. 35 seems to be the most popular. It's supposed to make the B string tighter and more punchy (it doesn't).
Electronics are all over the place as they are with 4-string. So, stuff like that as well as what type and gauge of string you will want are subjective to you. Actually, everything is.
I started on some kinda weird Fender copy. String spacing was way to narrow, causing me problems distinguishing between strings. Once I got my spacing figured out (17mm for me) I settled into becoming more familiar with my new fret board. I also found that 35-inch scale wasn't for me. I had to buy 2 Mike Lulls to discover this. Sad, awesome Basses. 34-inch scale fits me just fine. And all my 5's have banging B strings.
I have become a 5-string junkie. I believe that if you play a 5-string (or more) the need for a 4-string disappears. After all there is a 4-string in every 5-string. In every 6 or more string. It's there. With extended range Basses such as 5's, 6's or more you have so many options to make your playing easier. It's great to play across the neck instead of up and down. Runs are so much easier. Being able to stretch 2 octaves in basically one position opens up a lot of possibilities. And playing on that B string is awesome. I use a 135 for a B. While my low notes from Eb down to B are great. E and up are very full and thumpy.
Once I started down this path, I found that my 4-string instruments were going to suffer. After making the full commitment to 5-string, which was about 3 months into getting my first real 5'er, I let my 4 go. I now own nothing but 5's. 6 of em.
Regardless of the type of music you play. A 5-string will do it. Even if you're playing a song where you don't use the B string. Having it there keeps you conscious of it. Keeps the feel there. My band plays everything. Our original music, while being a bit more rock than the music we started this band with, I find I'm using my B string all the time. Even to play above E.
To answer your original question. How long to get use to a 5-string? Depends on you and you alone. Practice is the only remedy.
My personal opinion is that the 4-string is dead. Long live the 5.