If she's had that much time off, just bring her in, pick out her feet and then longe her both directions to let her shake the dust off. I wouldn't let her run around like a lunatic, but expect some bucks and kicks while she's letting off steam. After that, then take her back in to groom and saddle her. Once you're back in the saddle, my rule of thumb don't move on until horse is relaxed. At the walk, on a long rein, do shallow serpentines, subtle changes of bend, frequent changes of direction, whatever is necessary to keep her attention on you and not all the things she wants to spook at. She's already had time to be a good on the longe. Now it's time to work. Once she's relatively calm, then move up to trot and work on the same thing, relaxation. Move onto canter, repeat. Once your warmup is complete, work on whatever you had planned for that day.
The average horse can go about 4 months without losing significant muscle tone (very unlike us!), so she's probably more capable of hard work than you think. You know her best, so just ride until she starts showing signs of tiring.
Have fun getting back into riding!
You just have to see your distance...you don't have to like it.