Feel no fret (huh!).
It's the worst of myths that still perpeturating the net. that:
a) you should not change all of the strings at once, but one at a time.
b) you should take all off the strings when storing it for a long time.
People still can't get that these two advices contradicts each other. And yet they come with different excuses, and explanations of why these two rules applies. Basses in music stores has hanged around longer on their walls, than any of us has had any bass stored for longer periods of time under our beds. No reason for either. Your bass should be able to take ANY of these options. Either having it without strings for a long time, or strung up for a long time. Period. Otherwise your bass isn't worth any other sh*t than as a use as a door stop. Period. Go ahead. How else would you think maintenance should be carried out on any bass?