H1 Portability - Filing time limitation?

Lets say I am lucky enough to fall under the cap (which is a big question still) , go back to my home country and then clear my visa interview and I am back here again. Now, If i want to change my employer, do I have to wait till the April to Sept period next year to have my new employer apply for a H1 petition? or can i do it any time of the year? Does any one know?

H1B transfer, can be done anytime. Once you have a valid H1B, and you have been is status.

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