FWIW, Brexit is still not done formally. And nobody knows what will be immigration policies after Brexit. As I mentioned before, not every employer is keen to get permission from government to sponsor visa. So even if they have job opportunities and you are suited for it, things may not work out. One has to be on a particular visa type for 5 years to be eligible for PR. PR application also needs a letter from employeer mentioning you are still needed. Once you get PR, you are free to change jobs as per your will or even do consulting & contract work.
What Visa do you currently have?
T2 3 years
Simple answer to all these questions is, it depends !! First of all the employer needs to have a certificate from government to sponsor visa. Not many start-ups want to go through that process. Once an employer has certificate to sponsor, they need to advertise the job for some weeks (min 4 weeks, I think). If no local candidate is selected (local includes from EU as well, till formal Brexit happens) in these 4 weeks, they can hire international candidates. To hire international candidate, the employer has to apply for CoS from government. As far as I know there is a monthly quota for that, so it is filled by the time an employer applies, they have to wait a month for new quota be become available. Every job has a SoC code with it. Each SoC code has minimum salary requirements. Every year government publishes shortage occupation list. Min salary requirement for a job in shortage occupation list is less than normal. For each CoS, the employer has to pay some fee to government. Not all companies are ready for that. For switching sponsorer, the new sponsorer, should meet all conditions above & be willing for get a new CoS preferably in same SoC code. In such case, switching is relatively easy & its bit more easy for job in shortest occupation list. The main applicant needs to apply & complete the new visa application process to get new BRP. Only after this, he/she can start new job. The timelines depend on various factors & could be anywhere between 2 to 6 months. Hope this is helpful & answers your question. Please note, I m no immigration lawyer, so the information above must be taken with pinch of salt.
Thanks, So assuming the new employer has CoS and ran the labour test (4 weeks ad) successfully, how long would it take after that?