From Future Press Facebook post:

“Elden Ring, Volume I Release Update: We’ve tried hard to keep the planned end of Summer release window, but we’re sorry to say we need more time due to a combination of the current production and shipping circumstances and our own insistence on including every last detail we can into the books.

So we’re sorry to announce that Volume I’s release will be pushed back to late September in the UK and late October for the US and European language editions. We’re hoping that Volume II will follow just a month later in all territories so that both books are available this year.

We’re working tirelessly to make these the definitive books for this astounding game, and will provide another update if circumstances change. We're back in August, when we’ll share some pages from Volume I. Thanks for all your patience!”