5. In the following examples too the speakers are talking about a period that continues until now (recently/in the last few days/so far/since breakfast etc) 

Have you heard from George recently?

I've met a lot of people in the last few days.

Every thing is going well. We haven't had any problems so far.

I 'm hungry. I haven't eaten anything since breakfast.

It's nice to see you again. We haven't seen each other for along time.

6. We use the present perfect with today/this morning/this evening etc. when these periods are not finished at the time of speaking.

 I've drunk four cups of tea today. ( Perhaps I'll drink more before today is finished).

7. Note that we say 'It's the first time some thing has happened'

It's the first time he has driven a car.