H1-B Visa Stamping in London

[milim0]

I am a UK citizen with a H1-B. I am making plans to travel back in December to get a visa stamping.

I was wondering if there are only certain days where the embassy does H1-B visa stamping interviews? My Singaporean friend for instance said that they only interview on Tuesdays and Thursdays in the US embassy in Singapore as of two days ago

Also, how early were you able to book appointments?