I would sugest looking in April. The rental market is tough right now and you will need some time to find one that suits you. You may have better luck looking for one that is coming available rather than one that is vacant now.
I don't deal with many rentals but I would be happy to help if you are looking.
FYI. Your landlord may seem great now but be a good and careful tenant. Take LOTS of photos of your place and do a really good job cleaning up. Check the landlord/tenant laws for your state for return of security deposit, etc.
That aside, I'd start looking 60 days ahead of time - keep an eye on craigslist for anything really interesting. Be ready and able to put down a deposit for anything good so that others don't snap it up. Also place an ad of your own on CL. Refresh it every 3-4 days. Provide all the relevant details so that landlords will want to find you. Something like this will be pretty good. Just make it true and good: "Working professionals, non-smoking, no pets seek quiet 2-3 BR house. Towns and areas we will consider include XYZ. Excellent references and credit". Etc etc.
Don't forget, many times you can call a real estate broker or agent to help you find a home and this is at no cost to you. Typically, the seller pays a tenant agent's commission unless other terms have been negotiated.
Homes for rent are going fast these days. When you start looking, make sure you are ready to go and qualified or willing to give enough deposit to provide you some leverage for being the "winning" tenant for your new place.
Best of Luck