Two weeks ago I had an interview for a postdoc position. Because of the immediate need to fill that position, the committee decided, at the end of the interview, that I won't be considered for this particular position. On the other hand, they have multiple open positions, to be posted in the near future and I have a very high chance to be selected for one of them. The reason for not being chosen for the current position is they need to start it as soon as possible.
How long to wait before following up? and what could be the suggested format/etiquette of such a letter?