Elbow injury - how much of a setback?

[PersonaNonGrata]

So I'm waiting on diagnosis/MRI, but it's likely to be tendonosis/itis. Possibly distal bicep and one of the common forearm attachments too. Partial tears, severity unknown at this stage, but i couldn't lift a cup of coffee for the first week, so it ain't good.

Still in pain after more than 3 weeks, but it has improved
- Can't bench
- Can't overhead press
- Can't do pullups or chins

Bizarrely, narrow grip dips are fine now, and i can use weight with no pain - i can do high-rep shrugs with straight arms, but that's basically it. I don't dare attempt a deadlift as i might tear the thing clean off. Bench with the empty bar hurts, so i'm staying away.

Assuming I make some sort of recovery withing 3 or 4 months, how much upper body mass/strength am i likely to lose, and how quickly will i get it back? I have heard of the whole muscle memory thing, and people doing well after a layoff, but this is my first serious injury.