What's more idiomatic?

Here is more context Yankee

Tammy has been waiting for Tex at the library for an hour. Finally, he arrives / he comes at last.

Tammy (ironically): Take your time my dear Tex! Don’t you remember your own appointments now?!

Would you say 

a) "Don't hurry my dear Tex" instead of "take you time"?

b) "Do you forget your own appointements"?

See you

Hi Hela

There probably isn't any one comment that would be the "most likely thing" to say to Tex.  The comment(s) would depend the personalities involved and also on whether Tex had often kept Tammy waiting in the past.

I don't really understand why you want to use the word "own" unless you want to imply that he forgets appointments that he has no part in (but why should he worry about other people's appointments?)

I don't really see much difference between using forget and not remember here.  But to me the use of the word forget would usually tend to sound more negative even though it wouldn't be negative grammatically.

Assuming that Tex is often late for appointments with Tammy, here are some ideas (to be uttered with the appropriate level of sarcasm and possibly with a bit of eye rolling):

Tex, your memory is like a sieve.  Don't you ever remember your appointments?

Don't hurry just on my account, Tex.  (I've only been waiting for an hour.)

Just take your sweet old time, Tex... 

Do you forget all of your appointments (or do you just like giving me special treatment)?

Hi Hela

Translations can be tough, especially with such minimal context. 

What about these:

"Take your time, Tex my dear!  Are you now forgetting your appointments?"

Whether you use appointment, date or rendevous depends on the context.  The word appointment tends to sound the most impersonal and/or businesslike.  The word date is much more personal. The word rendezvous is often used when the meeting is secret.

Hope that helps.

Hi Hela

I didn't like the sound of the sentence with the simple present tense and the word 'now'.  In your sentence, the word 'now' suggests to me that this activity has just recently begun.  In this sentence, I'd say the continuous would be understood as a new, current "activity" (the forgetting of appointments).  But the continuous combined with the plural 'appointments' does suggest longish duration, and therefore possibly the beginnings of a habit.   And, don't forget:  the present continuous is sometimes used to complain about habitual activity.