I'd no sooner

This sentence should actually be re-phrased; "No sooner I'd walked into my office this morning, that I saw my boss waiting for me"
SL Don

Could anyone tell me the meaning of *I'd no sooner walked into the office this morning that I saw my boss waiting for me"?

Thanks

I think the original sentence reads more clearly if "than" is substituted for "that". That is, "I'd no sooner walked into the office this morning THAN I saw my boss waiting for me".

I'd just arrived at the office and I saw my boss was waiting for me. Or "...my boss was already waiting for me."

I thought it was going to be a discussion of strange comparisons like "I'd no sooner post on a forum than I'd have Michael Jackson babysit"

"No sooner" is an expression of future negative comparison whereas the norm is "as soon as" is used for "immediately upon".