Welcome to the forum
@Major210
Which insulin are you using?
If it’s a rapid acting one designed to apply to the following meal the general guide is that these take 15-20 minutes to ’get going’ though some members discover by a process of experimentation that slightly different timings (either waiting longer or not waiting at all) work better for them at different meal times.
I tend to find that at breakfast 20-30 minutes is about right and 10-15 minutes at lunchtime. But much longer than 5 minutes before my evening meal and I risk dropping low before the food is starting to absorb.
Depending on whether you are using rapid analogue, mixed, or long acting insulin things might be quite different though!