When I use modules like that, I drape a thin ribbon (1/4 inch wide) cut from plastic surveyor's tape across the each module cell. I place seedling compost on top of that. The ribbon goes down one side of the cell, across the bottom of the module under the compost, back up the opposite side of the cell.
Sow your seed into the compost/grow.
When you are ready to transplant it out, merely pull up on the two ends of the ribbon. Pops out, easy-peasy.
