AcceptWait is an Integer property that defines the timeout for accepting a new connection on the socket handle in Binding. AcceptWait is expressed in milliseconds. 

The default value for AcceptWait is ID_ACCEPT_WAIT, as assigned in the constructor for the object instance. 

AcceptWait is used in Listen to determine if the listener socket handle allocated to Binding is Readable. When the socket descriptor is readable, the new connection request is accepted using the handle in the listener, and the IOHandler for the connection is used to trigger the AfterAccept method.

TIdSocketHandle 

TIdSocketHandle.Readable 

TIdSimpleServer.Binding