Hm. I personally wouldn't put off ttc. Would you have to tell them straight away (eg for health reasons)? If not I'd go ahead with your plans and even if you conceivd straight away and tell them at 8 weeks, it will still be about 3 months after starting your job. Does the permanent job involve anything you've got to be trained for? Or is it what you're doing now but on a permanent basis? Either way, I don't think you should put what others might think before your own plans for a family. Although I know that's easier said than done. Anyway, good luck making the roghtdecision for yourself and DH.
PS: Check out my ticker!