Window size in TCP = 16 bits
That means receiver Window can have at max 65536 sequence numbers.
If we want to increase this winow size, 14 bits in OPTIONS can be used to increase this.
So in totality we wil be having $30$ $bits$ of window $(16+14)$
$B$ = 1048560 bits/sec
which is equal to
131070 Bps$
B*delay = 65535
delay = 65536/131070 = 0.5s = 500ms