"On line" bids generally will let you know fairly quickly if your bid is acceptable.
Short sales are a different matter. Be carefull.
If a seller is responding to your offer - not a bid - then there should be a response date in your offer. If you did not have a "Buyer's Agent" then you would probably be considered an unrepresented buyer and again would need to contact the seller's agent.
If there are multiple offers the seller will generally disclose that fact and usually move forward quickly with the best one.
It is important to give it some thought when writing your offer, as you certainly want to give the seller adequate time to fully consider your offer, but you don't want to be "locked out" of negotiating other alternatives for too long a period.
A professional realtor can certainly advise you in each situation.
will let you know fairly soon if your bid is acceptable.
I assume that you are not dealing with a short sale as that is a completely different senario.
a. On "normal resales" (i.e. private treaty, it is determined by the buyer's deadline included in the contract written for the offer.
b. If you are buying a lender-owned property you must allow a longer time, since institutions are usually slow responding to bids. Sometimes they may take up to a week to respond.
c. If you are bidding online (as you must to buy HUD foreclosures) the seller usually responds online the next business day.