question about 301

Hi I have website ( Domain A ) that for my main keyword is in page 2 , and i should do link building more on it for get rank 1 , now i want use 301 redirect to send this domain to new domain ( Domain B) .

if i do this and work ( link building ) on first domain ( Domain A ) , seo will work ? or i should first make seo on ( Domain A ) and after i got rank 1 make 301 redirect to new domain ( Domain B) . Thanks

You can do the redirect now and build all future links to domain B.

SEO will work and will be safer (for domain B as far as it`s hosted on different IP and is not associated with the domain owner of Domain A) with 301 redirect.