Concurrent filing options

Hi Guys,

I have read somewhere that according to concurrent filing rules, it is not necessary to submit I-140 and I-485 together and you can submit I-140 first, and then, later, while it is still pending you can submit I-485. I tried to find it on USCIS webpages, but did not see any clear statement confirming it. I know, this is a little bit strange approach, but in some circumstances it may be useful strategy, if it is possible. Can you confirm whether it is possible or not?

Thank you!