I would like to find a way to speed up time after the March 2013 update..

When The Sims FreePlay was first released there were a number of glitches that people could take advantage off, one of those was speed up the time. Here's how it worked:

https://www.supercheats.com/iphoneipad/the-sims-freeplay/804/how-to-speed-up-time/

Unfortunately this exploit has been patched a long time ago, and it is not possible to speed up time in The Sims Freeplay in 2020.

If you see any hack on the internet promising to do this for you, then our advice is to stay away and not try it as you could risk losing your Sims FreePlay account or your privacy if the hack asks for your personal or log in information.

If you've used a hack in the game to try to speed up time and something has gone wrong, well perhaps your game is messed up now. We advice to steer clear of websites offering hacks for games. Or anything that promises to give you free effects in a game that you would normally have to pay for.

The best legitimate way to speed up building or other processes now is with Life Points (LP). As you may know already these are hard to get in the game by playing, but this Tips page on our guide suggests some good ways to get a steady stream of new LP daily. They are a bit of a grind, but you do get LP:
https://www.supercheats.com/the-sims-freeplay/walkthrough/lp-strategy-mini-guide

You can also find some LP grinding Tips over on AppGamer:
https://www.appgamer.com/the-sims-freeplay/how-to-get-free-lifestyle-points