For many surgeons, they put us on liquids post-op to allow our stomachs to heal. Unlike with bypass, our pouches still grind. Most surgeons anchor the band by pulling the stomach over it and putting in a few stitches. By eating solid foods of any kind you are forcing your pouch to grind and putting pressure on those stitches that are trying to heal and form scar tissue to anchor them down. You risk pulling them loose, and needing another surgery to repair it. Liquids don't cause any grinding as they go right down...thus leaving our stomachs empty.
Now, not all surgeon's have the same post-op instructions and some people return to solids sooner than others. Each surgeon bases his or her post-op instructions on personal experiences of best outcomes. You should follow what you were instructed to do.
If you were to eat something that got stuck at this point, the pain and trauma from that could be extreme. I'd not want to risk losing my band because I pushed the envelope. I was one of the ones who was very hungry immediately post-op. When my doctor called at 3 days post-op to check on me I told him I was ready to eat my dog. He said that would be a bad choice, but since I was doing so well, I could move to full liquids a few days early. Mashed potatoes never tasted soooooo good!
If you are nauseous, there are medicines for that, call your surgeon's office and ask. Or ask if the saltines are OK. They might clear you for them.