Tier 4 dependent extension when main applicant gets ILR

[SHSol]

Hello,
I have got a question. I was on a Tier 4 Student visa expiring in January 2022, however I managed to get my ILR after 10 years of living in the UK a few weeks ago.
My husband was on my student visa as a dependent and his visa is still valid until next year. My question is if we need to switch his visa to a spouse visa now? Or can we wait until the visa expires?
I did not manage to find relevant guidance on hone office page.