How do you say when you do something you have not done it for a long time?
I found these terms on web dictionary. But I do not grasp if these are actually used and how to use it. Here are my attempt to describe with the terms. I am also appreciate it if you could give me other terms which actually being used.

I met her after a long interval. (I have not meet her for six months.)
I met her for the first time in a long time. (I have not meet her for six months)
I met her in ages. (I have not meet her for six months)

Question

How do you say when you do something you have not done it for a long time?
I found these terms on web dictionary. But I do not grasp if these are actually used and how to use it. Here are my attempt to describe with the terms. I am also appreciate it if you could give me other terms which actually being used.

I met her after a long interval. (I have not meet her for six months.)
I met her for the first time in a long time. (I have not meet her for six months)
I met her in ages. (I have not meet her for six months)

Answer

When I do something I haven't done for ages I say: 'I haven't done it for ages/a long time'; / 'It's been ages/a long time since I last did that'
When I meet someone I haven't seen for ages, I say: 'I haven't seen you for/in ages/a long time', 'It's been ages/a long time since I last saw her.

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