Changes in Work Permit and LTR processes

[i_worker]

In the past one can start to work for a new employer right after receiving approval letter from Work Permits (I am talking about in-country application only) and later receive LTR stamp (usually it took about 2-3 weeks). Work Permits has recently separated Work Permit approval and LTR application.
When can a person start to work for a new employer now?
How long will it take to get LTR stamp? I didn't found any timescales on the workingintheuk.gov.uk site

[i_worker]

Ok, after a bit of research, I found the following:
1. It seems a person needs to get both Work Permit and LTR before start working for a new employer.

you should not start or continue to work unless you have an approved IED and limited Leave to Remain approval

2. There is a same-day service for such applications, where you need to go in-person to one of HO centres (Croydon, Birmingham, Glasgow and Liverpool).

HTH