I don’t know anything about how effective that might be, but I imagine the logistics of transporting a live, deadly virus would be a nightmare.
That shouldn't stop us from brain storming, though, and allow experts to decide, if it's an interesting idea or stupid.
I did not calculated the chances yet but here is what my probability intuition is saying
Having 50% of population go through virus in one year creates a less fit environment for a more resistant mutation than having 50% of population being exposed to virus in 2-3 months.
Like more encounters over a shorter period of time is a good environment to allow survival of resistant mutations.