New rescue - 2 year old lab mix

I must begin by explaining that I really pushed my husband to let us rescue a dog. We looked into an adult dog so we could avoid the puppy training (since he's a first timer with dogs and I'm a first time dog mom - I grew up with them).

We brought Landon home (lab mix, 80 lbs) on 12/5, so he's been with us for a little under two weeks. He loves to sit with you on the couch, but he "paws" for attention and this bothers my husband since he accidentally scratched my face while doing this. Landon's housetrained and is fairly content in the house. We're getting a fence installed next week so I'm hoping he'll be able to run around and enjoy himself while not on a leash soon. He tends to pull on the leash while we walk him or sniff and freeze up, and whimper when other dogs bark at him, so walks aren't super easy right now.

Long story short, we learned he is food possessive and snapped at my husband and growled at me while he was eating. Since my husband was not on board with the adoption, I'm becoming more and more fearful that we aren't cut out for this.

I suppose I'm looking for some tips, anecdotes or just your story about how much time it took for your adult rescue to become completely part of your family. Yes, I'm aware it hasn't been the "3 weeks to adjust" period, but I'm just so anxious that I'm not giving Landon the environment he deserves. Thanks in advance for reading this and responding.