First, you need a dropper kit to accurately measure GH and KH, strips are terrible.
Second, no need to panic, nothing will happen from soft water over night. What you want to do is purchase some salty shrimp or shrimp king minerials to boost your levels. Get a TDS meter as well to help accurately remineralize your water. Amazon should have these to you in 2-3 days, which is totally okay.
Edit: Either a dropper kit for pH or a handheld meter is also fairly necessary.
>Is there any way to safely/quickly bring up the water hardness overnight?
You’d do more harm than good trying to do this. I recommend just doing a 90+% water change with a “stable” source (one that you know the GH/KH/TDS/pH etc), then re-mineralize as needed. This won’t harm your cycle as 95+% of the bacteria is *not in the water.*
> I’ve managed to accidently bring the gH in the tank from 8-10 dgh to around 2 dgh.
How?!?! the only way to reduce GH is to add RO water, or your tank is so heavily planted that it absorbs all the minerals quickly. Drift wood reduces pH but not GH. Did you actually mean pH here?
Bort_07 
First, you need a dropper kit to accurately measure GH and KH, strips are terrible.
Second, no need to panic, nothing will happen from soft water over night. What you want to do is purchase some salty shrimp or shrimp king minerials to boost your levels. Get a TDS meter as well to help accurately remineralize your water. Amazon should have these to you in 2-3 days, which is totally okay.
Edit: Either a dropper kit for pH or a handheld meter is also fairly necessary.
>Is there any way to safely/quickly bring up the water hardness overnight?
You’d do more harm than good trying to do this. I recommend just doing a 90+% water change with a “stable” source (one that you know the GH/KH/TDS/pH etc), then re-mineralize as needed. This won’t harm your cycle as 95+% of the bacteria is *not in the water.*
> I’ve managed to accidently bring the gH in the tank from 8-10 dgh to around 2 dgh.
How?!?! the only way to reduce GH is to add RO water, or your tank is so heavily planted that it absorbs all the minerals quickly. Drift wood reduces pH but not GH. Did you actually mean pH here?