Much to the dismay of many home buyers, a seller is typically going to respond to offers whenever they want to respond to offers.

This is largely a market driven phenomenon - it's a seller's market.  If there were more sellers than buyers, and thus a buyer's market, many sellers would likely feel more obligated to try to abide by a buyer's wishes.

Let's consider a few scenarios we might encounter in the current market...

Buyer:  I'm going to make my offer today, with a response deadline of tomorrow at 10:00 AM.  That will surely offer cause the seller to respond by that time.

Seller:  Three other agents indicate they will be sending offers tomorrow morning at some point - and this buyer with the 10AM deadline will likely still want the house tomorrow afternoon - so I'll respond to offers when I want to respond to offers.

...or...

Buyer:  They only have two offers as of this evening, and they told us they would respond by tomorrow morning, so I have a 50/50 shot at getting this house!

Seller:  I'll wait another day to respond to offers -- oh, what's that -- four more offers?  Fantastic!

...or...

Buyer:  The seller indicates they will respond to offers tomorrow at 12:00 PM so I'll wait and get my offer to them tomorrow morning.

Seller:  I have four amazing offers this evening - I'll go ahead and move forward with one of these offers.

So... yeah... it can get rough out there.

Sellers will (in the current market) likely respond to offers whenever they want to do so... and it might change to be earlier or later.

So, buyers, in most circumstances you will want to go ahead and make an offer (your strongest offer) just as soon as you are ready to do so -- and then patiently wait for a response.