Darryl’s Analysis

Expectations:
This rubber plant doesn’t look droopier than what I would consider normal range of leaf angles.  You’ve had the plant less than a month – it WILL grow and look different than when you first bought it.  You will lose older leaves too.

Environment:
Be sure to put the plant where it will have a wide view of the sky – right in front of your largest window is good.  If the sun will shine on it for longer than 2 or 3 hours, then block it with a white sheer curtain.

Effort:
I’ve never seen this kind of soil before.  It doesn’t appear to have a suitable structure for good tropical plant growth.  Good houseplant soil is usually made of peat moss, coconut coir, rice hulls, bark chips, and perlite (usually a combination of these things or whatever is available in your region).

Your watering strategy for this plant should be to water thoroughly and evenly (not just a small amount) whenever the soil reaches halfway to completely dry (not when just slightly dry).

You can learn the fundamentals of houseplant care in my online video course here

Or from my plant care book here