When should i send a thank you email to the recruiter?

If i had an interview today, when should i send the thank you note? I was told by the recruiter that considered candidates for the next round should start to hear back within the next two weeks on next steps. Should i send the note today (close to end of the week) or at the beginning of next week after the holiday so that my email is top of mind for him? I am worried that if I send it too early, he will forget about me amidst all of the other candidates that he is interviewing next week. But if I send early next week after the long weekend, i can be top of mind. I dont know.. help!