(this is a guess, I don't work at twitter) December: VP approves initiative January: PM assigned for initial research, weekly iterations on a product spec def

(this is a guess, I don't work at twitter) December: VP approves initiative January: PM assigned for initial research, weekly iterations on a product spec defining what considerations need to be accounted for February: Engineering lead assigned and starts to scope out technical implications on various datastores, weekly meeting with teams affected to see what's possible/what implications will be March: Engineering team established/actual work starts April: Proof of concept ready, comms start