So, I gotta leave my house at 5 00 pm
And I won’t be at the place where a lot of people will be untill 8 00 - 8 30.
So, I’m thinking two sprays of IS
and to finally try a little bit of Instant Heat (never tried it before)
Question; if I apply these at 4 00pm.
Will they last untill maybe 1-2am?
Depends what you’ll be doing between these hours, generally the oils will last longer than anything in the instant range. also depends on where you are and what you’re doing between these hours. Also if you wear any androstenone based products, the none does tend to stick around on the skin longer.
instant heat? never heard of it, but could definitely come in handy on a cold winter’s day or night 
typically the half life for the spray pheromones is about 4-6 hours, for most of the products,
in other words- after 4-6 hours half their effect is gone.
Instant Shine is a faster pheromone, so it lasts only about 3 hours.
depending on temperature, application points, your body chemistry, amount of sweat you produce, humidity, number of other people around you, and so on…
You could still have some effects left at 1 am
I have had some solid hits on A314 after about 11-12 hours before.