Hey Croweman
Before you go for a sail in the bay you can always check out the baywinds site, the bloke that created the site should get a knighthood:
earthsci.unimelb.edu.au/engage/dynamic-earth-updates/bay-windsNearly every kiter/windsurfer/sailor in melbourne uses this site.
Sandy pt is an awesome place to go & learn, again check the forecast and also very important check the tide - needs to be a low tide. Dont park too close to the water, unless you want to claim insurance. Plenty of friendly crew there as well (like most spots). You can get some of the flattest most perfect conditions in australia!
Some other places good to learn in melbourne are Hampton and St Kilda.
With Hampton you can park FREE

on beach road, rig on nice grass then carry your gear to the beach (dont sail between the flags if they are up). Best conditions are SSE to SW wind - West a bit too onshore. It has a fair amount of wave protection from Sandringham yacht club, but wind is a bit gusty. If you have a big fin (>500mm) watch the rocks, outside the breakwalls you are ok. A few kiters but they are cool.
St Kilda is also slightly wave protected but can have plenty of kiters if the wind is up. Go a but further up the beach, normally there are a few windsurfers out that can give you some advice. Good for SE to SW winds, also NW winds as well. Many a batten has been broken on the shorey in winds over 15kts so be careful. Primo scenery walking past as well


on most days when the sun is out. The water can get a bit skanky after a rain, be careful. You have to pay for parking on the water side of the road.
Be careful with your big fin (I assume you have a long fin and a shorter one) - when I started on my GO I nearly hit every underwater obstacle in the bay, I was forever fixing my fin. maybe use your smaller "shallow" fin when starting?
You have bought a great first board/rig combo!