You can get them pretty small and would probably do OK, but they do top out around 24". I have no idea how long it takes to get there. You might be able to get away with it with your timeline.
The only real cautionary, and that might help you decide, is that eels (all eels really) are notorious escape artists and a smaller tank is easier to escape. So an escape proof lid or canopy is really mandatory. An open top canopy is OK if it's tall enough and completely sealed around the edges when closed up.
If your tank is open top and you want to keep it that way then you might want to reconsider.
A friend of mine at work has one, he doesn't have a sump on his tank so he uses a hang on skimmer, he tells me he finds his baby snowflake in his skimmer every couple weeks.
