Evaluation takes minimum 25 working days if all your documents are correct and no issues with experience certificates.
In meanwhile you keep your certificates attested from HRD and MEA.
Once evaluation done. Ur sponsor will issue issue. U need to come over..
Things you need to get after you come to qatar.(takes around 15-20 days)
1. Attest documents again at Indian embassy
2. Attest documents at MOFA
3. Medical test
4. Apply for resident permit.
5. Appy for temporary licence.