I am catering a wedding of 130 people, Roasted Potatoes is one of the items, Wedding is at 2:00pm, can I cut and prep the potatoes the day before and leave in refrigerator in water, roast them in the morning and keep in a warming electric roaster? Will they loose there crunch this way? I have chafing dishes for serving but will only be using one for potatoes and will need to keep the rest warm. The venue does not have an oven.

Also, what would be your recommendation for how many pounds I will need? I was thinking along the line of 75 lbs? Bride asked for extra potatoes :-)

You can certainly save yourself time by prepping the potatoes ahead of time, and leaving refrigerated in water. Add 1 tablespoon of citric acid (concentrated lemon juice or white wine vinegar) to each gallon of water. To save further time, you may wish to add a step and parboil the potatoes, then roast prior to serving. If the venue does not have an oven you should be able to find or rent a suitable one to transport to finish on site. This will ensure the crispest end result. Otherwise the potatoes may not have the desired crunch if roasted prior and held too long. As for quantities, it’s always best to err on the long side. Idaho potatoes are always the least costly ingredient and it is not uncommon for guests to indulge once they see a delicious roasted potato as an offering – actually saving you some money as they satisfy their appetites on the side potato dish, and less on the proteins offered.

Here's a link to the proper steps to storing peeled potatoes, which should be helpful: https://idahopotato.com/dr-potato/proper-steps-to-storing-peeled-potatoes