A = attack time
D = decay time
S = sustain level
R = release time
forgive the obviousness of the above statement but lots of folks forget this definition and then struggle to understand why things do not work the way they want them to
given that you think you have your release covered, let's just look at the possible approaches to the first two event times
attack comes in a multitude of possibilities from instantaneous (starts immediately) to a slow increase in level over up to 10 seconds (depends on your adsr unit mostly). For 808 style kicks, you are more interested in 3 possible attacks: instant, quick and slow. the difference between them is a setting of 0, 1 and 2
decay can equally be anything from quick to moderate to slow, this time I would characterise them as being 0-2, 3-5 and 6 and above
choosing attack and decay times you can create some interesting yet powerful sounds.
sadly without knowing your synth environment the rest of what I want to write is moot