how far in advance can I/should I..

[littleredsquirrel]

whip cream?

chop strawberries and let them macerate?

Dinner party this evening and have a 90 minute window without the kids starting now!

You can do the strawberries now. Leave them at room temperature for 90 minutes and they'll taste so much better than cold out of a fridge. Cream you can whip now as well... it'll hold its shape in the fridge, no problem