I'm so very sorry for your loss. What a tragedy.
Your question comes up fairly often here, unfortunately. The consensus seems to be that it is never too soon if you feel you are ready. While a new pet is never a replacement, welcoming someone into your life who really needs a home can definitely help the healing process. Most people here seem to think that our bridge kids would want us to be happy and to open our homes and hearts to another animal in need. I'm pretty sure those people are right. Again, I'm so sorry for your loss.