Adverbial Phrases

Hello
My question is about exercise with the following adverbial phrases used with Present Perfect and Past Simple: up to now, in the last century, for three months, recently, this is the first time, lately, today, within the last months.

The question in this exercise is: What tenses would you use the following phrases with? Provide examples sentences. This is my sentences ( please mark it if you show that something is wrong with them and I would like to ask for an explanation of differences in meaning if one adverbial phrase is bound to two tenses because I have difficulty with it and I have any help by now) :

1) Up to now, I haven't received any documents from my bank.

2) Hundreds of nations have fallen to tyranny in the last century alone.

2) In the last century, half of the world's marshes were drained.

3) They've been together for three months.

3) They were together for three months.

4) It means that she was recently pregnant.

4) I fully appreciate the need to ensure appropriate conditions for mothers who have recently given birth.

5) This is the first time I have had a baby.

6) Well, I've been under a little stress lately.

7) Today, I have worked with a really good-looking man.

7) Today, I worked with a really good-looking man.

8) She submitted ten scripts within the last three months.

8) She has submitted then scripts within the last three months.