There is nothing wrong with being safe. Even with things lined up in the right direction, it is not a guarantee. After all, we are dealing with microscopic organisms and other things we really cannot see or measure. We are working with test kits that have their problems at times as well. Basically, what it often boils down to is trying to determine why things are not going as they should and then what will likely be the best way to get them back on track. Sometimes we have to make our best guess.
For squid here the goal is to try and fix things fairly fast before they can get out of hand and cause further issues. There are options, but not all will be feasible. I can set up a new tank and have it fully cycled instantly because I have many cycled tanks and also empty ones and plenty of spare hardware. Another fish keeper will not have those options. This means even in identical situations, we will likely take different actions to handle it. The nice part is we have such options.
If the bacteria added do their job, then things should improve pretty fast. On the other hand, if they do not there is always a fallback. At worst, there is always the massive repeated water change route. It can buy time to find cycled media. But in situations like this the most important thing is not to panic. Keeping a level head and not to jumping at any possible solution offered because one feels desperate to help the fish is important. Once something is put into the water, it is not so simple to get it out.
What I would like to be seeing in squid's next post is that his ammonia levels are not climbing sharply nor is the nitrite. If they go from .25 ppm to .50, I would be willing to watch a day or two as long as the fish show no sign of distress and the pH stays near 7. But if they moved much higher I would start to get nervous because of the direction and because the fish have already been somewhat "weakened". There is less leeway. But the next move should become clearer once the effect of what was done so far can be determined. If the ammonia is low but the nitrite a bit touchy- we can use a bit of salt as a bridge before we jump on big water changes. Odd as it sounds, resisting water changes, if possible, is the ideal. It will get one to cycled the fastest. But that doesn't mean not doing a big water change if the situation actually calls for it.
Trust me when I say pouring some Safe Start in a tank is a lot easier than doing a dozen 50-75% water changes
Especially, when it works well. Right now the main goal is not to have any more fish die, not to have them suffer any permanent damage and then to get the tank cycled as part of that. Lets see what squid reports today and then come up with the next step based on that