Time limit to enter after getting a Tier 1

[nokia33]

after getting a tier 1 visa is there some limitiion like you need to enter UK witin 1 month of 45 days etc ?

I want to enter UK only after I secure a job there, so I don't have to take the unnecessary risk of leaving my job at home

Thanks

[vinny]

See also entry period after tier 1

[nokia33]

Thanks

and what abt australia,
when you get visa by skilled immigration prog is there a requirement to enter australia within some specific months/time?