Tier 2 general visa

Hi All

Iam on a Tier 2 General Visa and eligible for ILR in July 2016. Now, i have some queries

If i decide to change sponsors, would I have to do the resident market labour test again? I have been Post Study work visa before and already through RMLT in the past when i got my current Tier 2 initial visa. Does it need to be done again?

Also, Does anyone know how much time does the new employer take to issue COS after you get offered the Job? I understand we get 60 days after the COS is cancelled. Is there a safe minimum time one can assume to get Curtailment letter from Govt if the current COS is cancelled? is it 3 months approximately?

Any advice/ information here would be useful and highly appreciated

you dont do the RLMT, its the employer who has to do it. All new employer who want to hire a tier 2 will have to do RLMT .. doesnt matter if ur previous or current emloyer had to get one done.
it depends on employer.. they might already have an allocation and it will take them 30 min to issue u one.. they might need to request additional cos for which it could take 2-3 weeks.
if your current employer cancels your cos, ur leave will be curtailed to 60 days from the date of issue of letter from ukvi.. how many days they take to issue the letter, however depends on them and no one can predict it.