Congrats on your seedlings. Serratifolia is one of the easier ones to get started with as it germinates quite rapidly.

I have several pots of clematis seedlings that have germinated this fall including what is supposed to be integrifolia the species and integrifolia Hanajima. The two oldest are Hanajima which I allowed to get three or four sets of true leaves before I started pinching them back. I started pinching because they were getting too tall for the light fixture they are growing under.