I agree with MidCakePa, it is not impolite.
~ Call and ask for the staffer, instead of a direct question, you might want to initiate the conversation, by simply stating I am just giving a follow up phone call to make sure that they have received your request for a nomination. At that point, they will acknowledge if they have. From that point you delve into it deeper by asking what is the timeframe to expect to hear from them.
~~ They may say, At this time we are unable to..., they may say you will be receiving something in the mail, or we have yet to finish up our initial review of all of the applicants.
Point being contacting them via a phone call instead of an email, allows you to get more info quicker than just an email.
~ There are some MoCs that do not do interviews in one day, but over a couple of dates. Thus, it might be that they are sending the notifications out tied to the interview date. In essence, in batches. Do not assume it is 1st come 1st serve. They will interview everyone on their list prior to submitting the slate.
I was also told that one of our senator (in the email that informed me of the interview) has 200 applications!
Applications or interviews? 200 interviews is a lot if it is just for 1 SA, but not a lot if they are saying for the entire group (USAFA, USMA, USNA, USMMA)...that is basically 50 interviews per SA. Interviews can last 10-20 mins. Do the math. 3 interviews an hr, means it would be 2 full days of interviewing for 50 interviews, or 4 interviewing groups simultaneously to get through 200 within 2 days of interviews.
200 applications, unless again it is for just 1 particular SA is not a lot for a Sen. VA has been known to be 750+ applications where many applicants will ask for a nom to 1 of 3 SAs. Remember not every applicant applies to multiple SAs. Our DS only applied for USAFA. Thus, for your Sen., maybe one SA has 200 applications, but another has only 125.
Many MoCs that do talk will state somewhere in their notification paperwork, or at the interview, if you have a nom from 1 source to notify them. Some will even go as far as saying if you do, they will not offer a nom. Bringing this back full circle to your post. It may be that since everyone you know has only 2 interviews with different sources, they may have x-checked their interview list before requesting interviews, however, without asking the cong staffer where you stand regarding your application you will not know.
Don't stress over this, it is going to happen or it isn't.