When to house hunt?

My husband, daughter and I currently live in an apartment. We just signed our lease for another year so it won’t be up until Jan 1 2019. I am due with baby #2 in August so we need to get into something bigger. If we plan on leaving in January, when should be start house hunting? To get out of our lease early we’d owe upwards of $10,000 which is absurd so we don’t plan on trying to break the lease.