What does with a couple of hours' notice mean?
1. Young people have become far more casual in inviting friends as well as relatives to meals. They will usually invite you with only a couple of hours' notice.

Does it mean they will usually invite you a couple of hours ahead of their party?

2. Young people often invite their friends with one or two hours.

Does it mean young people often invite their friend by using one or two hours?

Thank you!

Question

What does with a couple of hours' notice mean?
1. Young people have become far more casual in inviting friends as well as relatives to meals. They will usually invite you with only a couple of hours' notice.

Does it mean they will usually invite you a couple of hours ahead of their party?

2. Young people often invite their friends with one or two hours.

Does it mean young people often invite their friend by using one or two hours?
 
Thank you!

Answer

If you are given  notice, you were informed about it that amount of time before it was occurring. So yes, in that sentence, it means you will often receive the invitation within a couple hours of the parties start time.

Example:
"I gave my boss two-weeks notice that I was quitting." - You informed your boss you were quitting 2 weeks ahead of time.

"Young people often invite their friends with one or two hours." This second sentence does not make any sense to me. Provide more context to see the author's intent?