Awaiting offer letter from Accenture

Hi everyone, this is my first post. I was a campus hire and since it's been 2.6 years at Deloitte, I was thinking to switch. I had applied in Accenture, gave their technical interview and post that uploaded the documents in their portal (payslip, degree etc). The last action was on April 18th and later that I haven't received any communication. Someone said that an offer letter will take 2-3 weeks to generate. Is it true or else they will not send the letter. Also what hike can I expect, my current CTC is 9 with a base of 8.12. This is my appraisal month and I've received a strong rating and expect around 20% hike. Can I use this for negotiation if received.