Depends on who you count as a companion. For the Tenth Doctor, "The Day of the Doctor" was set between "The Waters of Mars" and "The End of Time", so, from his point of view, he would be between companions (between Donna/Jackson Lake/Rosita/Lady Christina/Adelaide and Wilf/Amy, depending on who you count as a companion). However, in the adventure itself Queen Elisabeth could be said to function as his 'companion'. Of course, he also met Clara in that story, so you could count her as his companion for that adventure.
- ↑ This could vary even further if you count the novels/short stories as canon