It will happen eventually because you cant have a "Baby Boy Lastname" forever. That said, we had names for two of our triplets almost immediately, and the third (the second boy) we had no clue. We spent WAY too much time looking and searching and deciding and then changing our minds. We got so desperate that we enlisted the help of a baby name 'pro' to help. But, DS4 was almost a week old by the time we decided and thats only because the insurance/ NICU/ hospital was demanding it. We went with one of the names given to us by the onomastic guru.
Just keep looking, it might be that one of the names you dont really like 100% now feels much better when you see him.