Advanced Impetus Flank March question

My turn to ask a question that I thought I understood but now some doubt has crept in and one of our clubmates has requested a clarification- Flank March sequence

1.Roll for FM arrival after all on table commands have activated

2. If successful at the start of the next turn the FM is placed on table. And here is the problem - does this placing on the table constitute the FMs activation or is it free to move and fight from that turn?

and a follow up - when roling for the FM do you need to advise your opponent which flank?

I start answering from the bottom, if I have understood correctly.

When you roll for FM (at the end of any turn) you just declare that you roll for a FM. You could even declare to roll for a Command than cannot be seen, as in theory you could have a full Command in ambush. There is always some kind of bluff in Impetus ;-)
You don't have to specify which side.

Once you have rolled the required dice to enter with that Command, you place the Units within the right distance and after that, your opponent can adjust the orientation of his units (if required). Ok, now the turn is really over. Time to roll for initiative of the new turn where it is supposed that the area where the flank march arrived is the area where both players have an interest to win the initiative.

Thanks Lorenzo that clears it up