Thermal paste does it need to dry?

I replaced the motherboard in a 2.16 GHz MacBook Core 2 Duo and applied the thermal paste in a very thin layer. I have never worked with thermal paste before and I would like to know if I need to wait until it is dry to install the heat sink. Or can I install it right away?

I could not find the answer in the thermal paste guide.

First I put so much paste on the processor that I had several circuit shorts. I removed it and did it again. Now I am nervous.

Thank you!