Hi Kiue
You made a good decision to buy a OZ PDRacer plans.
For me as a first time builder made a huge difference in building and even with such detailed description in the plans thetre is still a lot of room to learn and as you grow in confidence to experiment
The time to build the Racer depends on how much you pay attention to details. I don't know how many hours others spent but it took med arround 120 building hours to the stage whe I just need to paint the boat, whait for the warmer weather and go
I if had a full week off work and just work on the duch I think I could lower those hours a lot more. If you work an hour here and there then it takes more time to set things up.
Hint: Have a look at some posts on the forum when people started building and when they finish. It won't tell you the man hours but roughly the elapsed time. Don't look at mine time span.

Avg'08 to Mar'09
But as we had winter in between I wasn't worried.
Cheers and all the best - it is a great fun building this boat, I hope it wiill be the same with sailing it.