hello I had appointment with midwife yesterday and I'm 24+2 weeks pregnant and my midwife said I can…

hello I had appointment with midwife yesterday and I'm 24+2 weeks pregnant and my midwife said I can book for whooping cough injection from anytime now. I got leaflet before on one on my scans and I was told if I want to have that whopping cough injection I should have it from 28weeks pregnant so now I'm confused. I book for that injection for next week but I'm not sure if I should cancel it and move it till later on. Any suggestions?? please