Jumping from one airline to another while still a F/O carries risk. You don't know the politics and policies of your new employer, whereas you would know in your present company how long a command is likely to take.
It is much easier to move around as a DEC once you have 1000 hours command on type.
As for 3800 hours - that's not so much, especially if most has been in the RHS. Having said that, remember it's not the hours you put in that are important, it's what you put in to the hours.