Hi bazunka,
In my opinion plecos are unpredictable fishes. Some experience I had was sometimes the pleco survives the first few days n starts eating a lot, while others just starved themselves to death. So if your pleco starts eating the fish flakes, you are past the danger zone. One tip is to look at their stomach. If they r eating, their stomach will be a bit fill out; if their stomach is flat then they r not eating well. Just let it feed on its own and cross ur fingers. But most of the time they wil eat
funkychips.