Pre-allocation of disk space for a new VM

Rather than expanding on demand, I'd like the setup to offer to pre-allocate all the disk space on the host (Mac in my case).

The reason is that a SMB server running in a Debian VM can have multi-minute flushes. This means that Time Machine gives up as the round trip for a SMB flush (or write) times out as UTM is expanding the disk.

If it was pre-allocated, this latency would not happen.