You can never really catch it.
The guys have correctly advised you that the only option that works is an order you have prepared in advance, anything else will already be a bit of a missed opportunity.
You should understand that the market will always "cheat" you and it will be hard for you to control everything that happens, which is why all you can do is properly allocate the capital you will keep safe so that you always have some chance to reassure yourself or change your mind if something unexpected happens or something that was not anticipated before.
This is one of the most difficult things in our business, but it is definitely important to accept and understand.