Visa Sponsorship Predicament

Hello all. I have a question about sponsorship and my work visa.
So, as of right now I have both a job and a work visa to teach as an "Instructor." (I'm working for an ALT dispatch company and I'll be in Ami in Ibaraki.) I just got my, but I haven't signed it yet; I am supposed to sign it at training. Here is the thing, because of the current situation in Japan, I have a lot of family members urging me not to go. This wouldn't be too much of a problem, except my aunt was going to loan me some extra money for start up. However, she is not going to do that anymore. She wants me to wait about a month before she'd loan me the money again.
My question is this: if am not able to postpone my arrival with my company and they take away the job offer, will my work visa become nulled immediately? I have yet to enter the country, so my passport still has the work visa and the COE with my company as the sponsor. I'm just trying to find out if I should prepare for starting the whole visa application over again?

Thanks for your time.

Your visa's period of validity, i.e. the time frame within which you can enter Japan, should be mentioned on your visa.

It's valid for three months (from March - June). I was just wondering if things do not work out with postponing my trip further and I have to break ties with my employer/sponsor if they'll void my visa with immigration before I get there. That's my main concern. Thank you for your involvement, though.

It would be something new to me that a sponsor can cancel a visa after its issuance. But I am not an expert.

Well that sounds about right, then. I'm sorry if the question was simple and kind of dumb. I was just confused about this whole situation. Thank you for your help!