From:
http://www.asb.unsw.edu.au/currents...formation/Pages/newundergraduatestudents.aspx
it says that new undergraduate students doing bachelor of commerce/economics must enrol in ACCT1501, ECON1101, ECON1203 and MGMT1001.
Do we have to enrol in all these courses in semester 1 or can we do some in semester 1 and the rest in semester 2?
Enrol in those 4. You don't have to like people have said, but it helps for your later subjects. Additionally, you get an extra semester to ponder about your other flexible cores and majors. The only reason you'd enrol differently would be if you were planning an actuarial studies major. There is more info on that here:
http://www.handbook.unsw.edu.au/undergraduate/plans/2012/ACTLA13502.html
Happy studying
Edit: Actually, another reason you could potentially consider enrolling differently is if you were definitely not doing any MGMT/ECON/ACCT major (1 of them) and were planning to do a language as a 2nd major, in which case it'd be beneficial to enrol in the (Language) A course.
So for example, you were thinking of doing Actuarial and French as your majors under commerce. You should then enrol into Actuarial Maths A, French 1A and two of MGMT1001, ACCT1501 and ECON1101. In semester two, you'd enrol in French1B, Actuarial Maths B, Actl1001 (flexible core) & the MGMT1001/ECON1101/ACCT1501 core that you didn't do.
You'd still have flexible cores left, the rest of the requirements of your French major and the actuarial major. This way though, you'd not be set up for failure in terms of prerequisites.