Although it may look fully developed after 20 seconds, it isn't - it's just the high contrast caused by the safelight that makes it look that way: as Jurej wrote, it still needs more time to reach a good black - for MGIV RC it will be fully ready after 45-60 seconds at 20 deg C in MG developer at 1+9 strength (1 use 60 seconds + another 15 seconds draining before plonking it in the stop bath).
The time does seem short, but it depends on what size you are printing at and what wattage your enlarger lamp is (I see from your previous posts that it looks like a colour diffuser head) and how thin your negatives are etc.... More detail would help, but looking at it, 3.5 seconds does seem very short assuming an 8x10. Are you dialing in contrast settings using the head? If you use the equal-exposure chart in the Ilford PDF (where you dial in both Yellow and Magenta for each grade) that introduces a useful degree of neutral density. If you are not adding any filtering at all, you get grade 2, but the light is much brighter, which may explain your short time.
Is the border of the print that was under the easel blades also grey? If so, you have fogging which will explain the lack of whites - check for light leaks and that your safelight is not too close to the paper at any time - most safelights like to be a minimum of 3 feet away from the paper. If that is OK, it sounds like too low a contrast: try dialing in filters to achieve grade 4. Make new test strips at this grade and make a print. Any better?
Don't be stingy with the test strips - use at least a half sheet of 8x10 paper for now until you get the hang of things. That will let you see better what is happening to the highlights and shadows for the different times and different grades. You can refine your technique later.
If none of our suggestions help, try again but this time list everything you do and report back with the list: someone may spot the problem with more detail....
Good luck! Bob.