The young midfelder, 18, has been part of the main group all summer and as well as training, has featured in all three behind-closed-doors friendlies to date against Southend, Reading and Brentford.
The Academy product made his debut against Burnley in the FA Cup last season and his performances have been rewarded with a new contract until 2019.
“Pre-season with the first team has been a big step, I think I’ve coped well and I’ve learned a lot,” said Josh.
“When you are with the first team every day you learn so much including how to cope with things on and off the pitch.
“To be with them every day has been a big boost to my confidence and hopefully I can make my mark as well.
“We’ve some massive games coming up including the MLS All Stars and the Audi Cup and I’d love to be involved. If I am, I’m sure I will gain valuable experience.”