Confusion about physics grad school.

[v2536]

Hi I am currently studying at university of melbourne (Australia) major in mathematical physics and I just finished my second year. I plan to continue my graduate study in physics in US because i think the reputation of universities there are better.
According to what i read from Caltech website, it says that I only need a B.S. for their Ph.D. program. But what confuses me is that undergraduate degree is only 3 years here in Australia as oppose to 4 years in the US. The requirement for Ph.D. program here in melbourne is I have to complete an honoure year (which is an extra year after 3rd year, focus on research i guess) unless if I've got a good enough grade then I can go straight into Ph.D. after my 3rd year (which i think i have that so far). If I want to apply for grad school after I finish my 3rd year then apparently I need to prepare for GRE test and other things now, but the question is:
Is this really the right time?
should I give it a try anyway?

I've done a little research for my professor in my second year and also currently working for another professor as well in this summer break, helping out with stuffs. I also have other I have to do so I don't want to put my effort into GRE preparation if that only going to waste my time.
Please give me some advice, thank you :)

 

[R.Mesri]

Yes, it is the right time to start preparing for your GRE test. Although you may not feel like it, making sure that you are fully prepared for the test will be beneficial in the long run. Taking the GRE now will ensure that you have enough time to practice and review all of the material before the actual test date.Additionally, you should begin gathering the necessary information and materials for your graduate school application process. This includes gathering transcripts, letters of recommendation, research experience, etc. It is important to start this process as soon as possible so that you are able to submit a complete and competitive application.Good luck!