Swarming is a hot topic at the moment and once which causes many beekeeping beginners and novices stress.
Bees can raise a queen from a day old larva (i.e. 4 days after the egg was laid) and the cell will be sealed on the eighth or ninth day after the egg was laid. So at this time of the year inspections are recommended at four or five day intervals – we all have experience of going back a week after a previous inspection when no queen cells were seen to find that they now have sealed queen cells. At which point the old queen has usually left the hive.
Clipping the queens wing, or wings prevents her flight and so while she may leave she will fall in front of the hive* and after a time the bees that left with her will return until the first virgin queen emerges when they are likely to leave in a cast (secondary) swarm. But this can give you a few extra days and if the the attempted swarm has been seen then you have confirmation that the bees are intent on swarming and not superseding the queen.
The Demaree method can suppress the swarming urge – which simply destroying queen cells will not do – and requires the minimum of additional equipment. The rather good Barnsley Beekeepers Association website has this excellent description of the Demaree method.
The more adventurous beekeepers among you may wish to try using the Snelgrove method – also described on the Barnsley Beekeepers Association website.
*this may seem cruel but remember that survival rates of swarms are very low and swarms can find homes in a location causing problems for householders. So letting them go is not a good option.