How far ahead do you want to make them? Do you have your fillings selected already?
Hope some of this is helpful:
If you can, wait until the day of to put the spreads on the bread and assemble the sandwiches. You can freeze the bread weeks ahead and take it out the morning of, or night before to let it defrost.
As far as the spreads go – not sure what you have in mind, but here are some thoughts on some typical spreads:
- Egg salad – make day ahead, cover tightly and refrigerate
- Chicken salad or tuna salad – two days ahead, cover tightly and refrigerate
- Smoked salmon with crème fraiche, or else plain yogurt mixed with a little sour cream and dill. You can freeze the packaged smoked salmon well ahead, defrost in the fridge the night before, cut into smaller slices for sandwiches the day of. The crème fraiche can be made ahead or purchased a few days before. The yogurt/sour cream mixture could be made the day before, cover tightly and refrigerate. You may need to drain some water off the top on the day of.
- Cucumber sandwiches – the day before, you could slice the cucumbers. Cucumbers drain a lot of water, so line a baking sheet with paper towels or a not-fuzzy dishcloth. Lay out the sliced cucumbers in a single layer on the sheet. If you fill up the sheet, add another layer of paper towel or dish towel, then just keep laying out cucumbers. Cover the final top layer with paper towel or dish towel. Put tray in refrigerator, keep very cold so cucumbers don’t wilt. Assemble sandwiches the next day. There’s a fun Hotline thread here about cucumber sandwiches: https://food52.com/hotline...
Another time saver is to get out your serving trays out and wash them ahead of time. Stack them and cover with a towel to keep them from getting dusty. I know people who have separate dining rooms, who will set a big table a week ahead and cover it with a sheet. :-) Saves a lot of time later on.
We occasionally did tea sandwiches for my 30 yr. catering co. Fillings were all made ahead (mushroom duxelles, curried egg salad, salmon mousse, etc. (no cuke) 4 or 5 days ahead of the event, no problem. One day before, the sandwiches were made and cut and layered with damp doubled paper towels in a fish bin (or on a sheet pan,and then saran wrapped.) and refrigerated. The amount of filling is pretty mniscule so soggy bread was never an issue, and drying out was not an issue because of the paper towels and containers. We preferred to use Pepperidge Farm thin sliced white and Pepp.Farm thin sliced wheat. You can cut the sandwiches into 4 triangles or 3 bars- for variety.