I will be flying on March 31 to be able to obtain QFF Gold.

I will be flying on March 31 to be able to obtain QFF Gold. However, status credits won't show for another few days (status credits expire on March 31 every year). Would I automatically obtain Gold say few weeks into April or do they have to be accrued in my account before the expiry date in order to achieve next status up? Your feedback is greatly appreciated.

I did this last June. I did OOL-SYD-OOL in one day, and the last day I could. I Dropped back to Silver the next day, then the points were credited and I was put back up to gold. Call QFF if you have any problems. Although I don't anticipate any. 

I flew on the last day of my QFF status year (31 Oct 2012) and obtained enough status credits on that day to move from gold to platinum.  It took 2 days for the SCs to appear in my account but when they did, I was moved to platinum for a total of nearly 2 years (exp 31 Oct 2014).  It seems this happened because any increase in status is for a minimum of 12 months, so I benefitted from an increase for the rest of my membership year (by that time it was 11 months and 28 days) PLUS the minimum of 12 months!  Not sure if this was a glitch or not, but I sure didn't complain.  I don't think this would work though when maintaining status rather than attaining a new status.

That does seem unusual Samson, I'd think it should go until 31st October 2013, but I wouldn't be complaining either!  I went from silver to gold a month before my 12 month expiry date and it expired 13 months later, so you are lucky in that I regard.