There's no specific timeline for altcoins commence bull, it could be now? Tommorow? next week or next year. That is always depending on the frequency of the buy and sell orders, and could trigger more demands once the community is always active.
There is no timeline, but there is a cue to when altcoins do spike, and I think that is when bitcoin is going sideways, the bull run you talked about here, I don’t know if you specifically means normal bull run that affects altcoins individually, or the general bull run. If it is the general bull run, the only timeline for them is when bitcoin is going sideways, and now that we are already in bitcoin bull run, I expect it to go sideways very soon for most altcoins to start surging high.
For the individual bull run, I agree to that fact too that anytime can be there bull run, it all depends on the project and activeness of the developers, the product too matters a lot, because that is what the investors will look at first to determine if they will have interest in the project or not either for a short term investment or a long term investment.