Is it more effective to do reality checks whenever I remember, or as a fixed schedule (i.e. alarm every half hour)?

Ive been practicing pinching myself and trying to poke my finger through the palm of my hand whenever I remember (which is very frequently) for about a week now, but I still don't do it in dreams.

Looking at the time and then looking back has shown some progress though, (Ive done it in dreams twice now), thats why I ask, should I turn this into a regular scheduled thing? Or just whenever I remember?