The concept of time in the Afterlife is very different to ours, they do not have calendars or clocks and how long they are passed is of no meaning to them.  Some Spirit connect with us in a very short space of time and others can take much longer.  I believe this has to do with their ability to accept that they have departed this life and of course, can have a lot to do with the circumstances of how they passed.  Spirit want very much to let us know that they are still with us, still love and care for us and to reassure us that they are in a good place surrounded by family and friends who passed before them.  We do not disturb or hold them back by wanting a sign that they are happy.  Never be afraid or unsure of asking your Loved Ones to let you know they are still with you, they are very happy to do so.  Don’t worry if it sometimes takes time, as soon as they are ready and able to do so, they will.