Taking extra insulin during a meal

If after say an hour or so into your meal it looks like you might have miscalculated and you are going high, how do decide on topping up to avoid stacking? I believe you have up to 2 hours into your meal when you can add some compensating insulin?

I don't know about other people but for me a spike after food is normal even with the right amount of insulin. I'd not look to correct until at least 4 hours after eating just in case the correction sent me low.
I'm on Novorapid in case that's relevant!

Thanks for taking the trouble to reply Dyl, however, whilst I agree this is a DAFNE principle, I seem to recall that my Consultant gave me this advice but on reflection I am not so sure