Yeah, the previous two was at very specific time frames and did very specific things. We're not in any of those time frames. The last one was 3 years before FO4 and there's a quest dealing with that, which I won't spoil.
However, you could retcon? It doesn't do a lot of harm. First BOS patrol was successful in specified thing, second failed, third was Danse. I'm not trying to argue, I don't mind if you retcon, I'm just wondering how close to canon we're staying. If we don't worry too much about specific little lore you can be more flexible in triggering certain events early or having more brotherhood earlier.