How to say: 'Can't wait to finish college' in Japanese
Here's what I know:

(Looking forward to it...)
楽しみにしています。

(Can't wait? I haven't used this before, is that correct?)
待てない！

(to finish college)
大学を卒業している。

Attempt to put it together:

大学を卒業するとき、待てない。

I have not combined different thoughts/actions in a single sentence much so I am trying to figure it out.

よろしくおねがいします。

Question

How to say: 'Can't wait to finish college' in Japanese
Here's what I know:

(Looking forward to it...)
楽しみにしています。

(Can't wait? I haven't used this before, is that correct?)
待てない！

(to finish college)
大学を卒業している。

Attempt to put it together:

大学を卒業するとき、待てない。

I have not combined different thoughts/actions in a single sentence much so I am trying to figure it out.

よろしくおねがいします。

Answer

There are several ways to say it, like kei.isomura-san said. 
If I was looking forward to finishing collage, I would translate "can't wait" as 卒業するのが待ちきれない。

The direct translation of "I can't wait to finish collage" is 卒業することを待つことができません.

I hope this was helpful.

Answer

Thanks for the response, kei!

So

'大学を卒業するとき、待てない'

makes sense but

'大学の卒業なんて待ってはいられない'

is better, is that right?

I need to read about 'なんて' because I'm not sure what it means.

Thanks again!

Answer

You are correct / good try and reach to answer 
We say this way 
"大学の卒業なんて待ってはいられない”　
your analysis is good . Try to continue  this way..