H1B Regular Processing - Receipt Notice received on 6th May, next steps?

Dear Friends,

I received Form I-797C, Notice of Action on May 6th mentioning my Receipt Number WACXXXXXXXXXX.

It says the receipt date April 13 and notice date April 24.

Now, what I understood is two major steps:

  1. They will adjudicate the whole petition. If everything goes well, they will issues me H1B approval with I-129.

  2. Then I need to fill up DS-160 and appear for the interview at US Consulate.

I have read the processing time of approx. 2 months.

So, when that time starts? from the receipt date or notice date or from the date when I got the information?

Please help me and also let me know what I understand above is correct?

Now, is there any chances that my petition get rejected by any reason??