@hida_berserker
Upon grant, bibigyan ka nila na Initial Entry Date (IED) which kailangan andun kana on or before that date. May mga calculation theory sa IED, some say 1 year from either police or medical clearance, or 6 months if meron ka medical findings, but decision ito ng Case Officer.
Now if in case na mabigyan ka ng grant and 1 month or less nalang, sometimes bibigyan ka ng IED waiver, which means pwede ka lumagpas ng arrival mo from that IED. Meron din mga migrants suggesting that if hindi ka talaga maka meet sa IED, pwede ka mag request sa waiver na ito with valid reasons like medical/health, or your case na contracts, atbp.
Here's one example sa request na ginawa ng isang migrant:
http://www.expatforum.com/expats/australia-expat-forum-expats-living-australia/954522-facilitation-letter-exemption-initial-entry-requirement.html