Thanks everyone who has mentioned this. I noticed a end of month pattern to needing prednisolone after worsening asthma this year for several months (but not second last month after ENT surgery?) and again going downhill last month.
The bit I'm not sure about, it is not the week before but more like mid+ cycle of a 4-5 week cycle.
Also had stopped pill this year and asthma is worse since?
I am keeping a peakflow diary which seems to correspond.