Limit Pubsub items by date

Hi all. How can I limit the number of items received from a pubsub according to date?

I only found node.getItems(maxnumber), but the problem is, I have no idea how many items have been sent since the last time the user was offline…

Is there any way to get the items since a certain date, for example node.getItems(“2015-10-10 08:51:30”)