SystemC simulation Kernel
I just compiled and ran the following code (I added a simple sc_main to your example) against System 2.3.1:

#include &lt;iostream&gt;
#include &lt;iomanip&gt;
#include "systemc.h"

using namespace std;

SC_MODULE(mon)
{
    sc_in&lt;bool&gt; A,B,F;
    sc_in&lt;bool&gt; Clk;

  void monitor()
  {
    cout &lt;&lt; setw(10) &lt;&lt; "Time";
    cout &lt;&lt; setw(2) &lt;&lt; "A" ;
    cout &lt;&lt; setw(2) &lt;&lt; "B";
    cout &lt;&lt; setw(2) &lt;&lt; "F" &lt;&lt; endl;
    while (true)
    {
      cout &lt;&lt; setw(10) &lt;&lt; sc_time_stamp();
      cout &lt;&lt; setw(2) &lt;&lt; A.read();
      cout &lt;&lt; setw(2) &lt;&lt; B.read();
      cout &lt;&lt; setw(2) &lt;&lt; F.read() &lt;&lt; endl;
      wait();    // wait for 1 clock cycle
    }
  }

  SC_CTOR(mon)
  {
    SC_THREAD(monitor);
    sensitive &lt;&lt; Clk.pos();
  }
};

int sc_main(int argc, char **argv) {
    mon m("m");

    sc_signal&lt;bool&gt; A,B,F;
    sc_clock TestClk("TestClock", 10, SC_NS, 0.5, 1, SC_NS);

    m.A(A);
    m.B(B);
    m.F(F);
    m.Clk(TestClk);

    sc_start(50, SC_NS);

    return 0;
}


and saw this output:

    SystemC 2.3.1-Accellera --- Nov 29 2014 15:29:06
    Copyright (c) 1996-2014 by all Contributors,
    ALL RIGHTS RESERVED
  Time A B F
   0 s 0 0 0
  1 ns 0 0 0
 11 ns 0 0 0
 21 ns 0 0 0
 31 ns 0 0 0
 41 ns 0 0 0


There is output at time 0, as you were expecting. I'm not sure why you aren't seeing that. Perhaps there is typo in your code. Maybe try again with the example code I included above?