Probably not. Antony was expected by pretty much everyone to become Caesar's heir, and his will was changed secretly after the Spanish campaign. I wrote a writeup here which I think should answer your question--if you're still confused, or if you have more just fire away!

Most of our sources claim that Octavian only learned he was Caesar's heir after the assassination and that the adoption took everyone by surprise. For example:

Suetonius, "Life of the Deified Augustus," 8.2 (trans. J.C. Rolfe):

"As soon as he learned that his uncle had been slain and that he was his heir, he was in doubt for some time whether to appeal to the nearest legions, but gave up the idea as hasty and premature. He did, however, return to the city (Rome) and enter upon his inheritance, in spite of the doubts of his mother and the strong opposition of his step-father, the ex-consul Marcius Philippus."