Im kind of in the same situation, I am doing a TY year now and looking to start some moonlighting during pgy-2. After talking to some recruiters, it would be good to do PALS, ACLS, ATLS and get step 3 out of the way before u try to get your permanent license after u complete your intern year if u are looking to moonlight in ER. Most places prefer pgy3 though, however, i know of people who started the summer after their intern year.
If u dont want to do ER, u can look at other things after u get your license like urgent care, prisons, nursing homes, babysitting MRI scanner, dictating.
I liked that I did a TY year, cuz it gave me the opportunity to rotate in medicine, peds, surgery (take trauma call) and ER. u wont get that variety if u do prelim medicine.
PS- oh yeah just try to get some central lines, intubations, chest tubes, suturing in during your intern year.
later