Bluetit nesting in titbox temporarily too low down - can it be moved higher

I hung a tit nest box on hook under birdfeeder table temporarily to keep it off the ground after cleaning it but bluetit interested in it. If they start before I can get windowcleaner to hang it higher up do I leave it. Only 2’6 above rockery and neighbours cat comes in a lot. 

Cant afford to put food in birdfeeders, just a bit on the ground so unused.