You will know when the time is right to get another dog. You will see something and it will just click that this is the dog meant to be with you. Don't feel guilty about getting another dog, I know we never really get over the loss of loosing one but we do learn to live without them. We have no choice. Another dog will fill the void and you will grow to love it as much as you did your other one. It hurts loosing one but its the price we pay for loving and having them in our lives.
But I would caution you on getting two a the same time. They will bond to each other, more than to you. Plus if you get two puppies they will grow old at the same time and probably loose both within a short period. If you want to get two wait until the other has bonded to you, the two will still get along and love each other but they will love and bond with you more if you don't get them at the same time.
He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion"