Exactly. This is always my first turn buy as well, and it is for about 90% of my opponents, too - and if the Allies haven’t destroyed both transports by turn 3 or 4, they are in trouble.
Usually I purchase an extra sub, not a transport. Of course, I would also have to do this with a bid.
TG is closer to the mark - you should send 2 inf a turn as long as you can… which will only be 2 or 3 turns.
Thanks. :)