So lets say we want to make a TCP connection with a server

since in TCP we double the sending segments(the number of segments we send or window) after receiving the acks because of tcp congestion control (before reaching the threshold), but does the first segment sent by the sender in the 3 way handshake counts?

Basically what I'm asking is after receiving the ack from receiver in the second phase of 3 way handshake which one these we would do :

1. send the ack only

2. send ack + 1 segment

3. send ack + 2 segment

or maybe non of the above?