How do I Randomly and Increasingly Spawn Enemies?

So I have this game idea where it is basically a stationary player (in the center of the layout), and you can rotate the character via a virtual joystick (Bottom left of the layout) to make the character look in 8 directions. The idea being that enemies can continuously spawn randomly from either of the 8 directions, while over time the spawn rate increase. After they spawn they start coming toward you (I can do the part where they walk toward you but not the whole increasingly faster + random enemy spawns).

I will provide a layout of what I mean when I can as that is on my other computer. Thanks in advance!

you need 2 or 3 variables

varTime, varSpeed and varSpawn

In this example, I use the time variable a little bit different (but for more control you could count the time played and on certain thresholds increase the speed and spawn variable)

Edit: there is a mistake in the picture it should read every 7 seconds > ADD varSpeed 3

Thank you so much fm4fanAT that is exactly what I was thinking about! Your the best man! Much love.