Bbbbbrrrrr for nematodes to thrive, they need a consistently damp environment, particularly in the top couple inches where they are most concentrated. If the soil dries out quickly, especially right after application, nematodes will die. preventing the soil surface from drying out too fast is essential to keep them active and prevent death by desiccation. The fluctuating moisture levels in small seedling pots are often too volatile for nematode survival.
Add inorganic mulch to prevent rapid evaporation of topsoil while still allowing plant to grow normally. You don't want a dome, but if you need to increase rh you can add half dome, where you leave the top completely open. This "lip" will create a artificially high RH preventing rapid drying, giving nematodes time to settle.
I'd fetch some yellow stickies, normally does enough to control population, once she hits the veg stage then I'd add my nematodes unless the situation is dire. Gluck