It wouldn't hurt her if you gave her a bath now, just use a mild (puppy) shampoo. Nebo gets a bath about once a month, it doesn't have to be that often though. I don't think she'd need professional grooming, her fur looks pretty short....if it does grow long just keep it brushed out and maybe trim around her paws, clip her nails. If she grows to be 150 lbs like you estimated professional grooming may be needed as that's a pretty big dog for a bathtub. If she's just a foster I'm sure she'll be adopted before then though!