no hydrometer

[Globex0001]

I brewed a Dubbel saturday night, during the brewing I broke my hydrometer. Will not have a chance to replace it till this friday.(six days after brewing) The only thing I could think of was to grab a half quart of wort put the top on it and stuck in the fridge. If I take it out on friday let the temp come up and take a reading will this come close to a reflection on Original Gravity? Do I need to shake it up? Or do anything else?