OmegaUnderground reports that the production has been pushed back to October 23rd, 2017 now and that it is more than likely due to the demand for crew members since there is so much filming going on in Atlanta for Avengers 4 and Ant-Man and the Wasp. There has also been some speculation that we could see some Marvel characters make a cameo in Sony's standalone Venom movie, but nothing has been confirmed as of this writing.
Venom was originally supposed to begin production on September 1st, but a report posted a week earlier suggested that the studio was still looking for crew members. According to the initial report, Columbia Pictures was accepting applications for all crew positions for the Spider-Man spin-off movie. It's now early September, and production has yet to start. The movie is also expected to shoot in New York City as well and the report from Omega Underground states that production will begin in both cities on October 23rd.
It has been rumored that Carnage and Anne Weying (She-Venom) will be in the movie, but nothing concrete has been announced. Chameleon has also been teased. She-Venom does seem pretty plausible since Anne Weying is the ex-wife of Eddie Brock and an early casting call leaked over the summer hinted to her inclusion in the movie. Carnage on the other hand seems like a no brainer, especially since director Ruben Fleisher wants to take the Venom character back to his horror roots, plus fans really want to see Carnage go against Venom. It has also been rumored that if Carnage does show up in the movie, that it won't be until the end, which could tease a second movie. Riz Ahmed(Rogue One) is attached to the project and many assume that he could be playing the part of Carnage, but no official announcements have been made.
Credit Movieweb.com for this article