When my 2000 Odyssey sits for 1 day, its slow to start next day

With vehicle operating, take it to local auto parts store and have them wheel their diagnostic cart out to vehicle. They will check it complimentary and likely find your issue.

Can you jumper the fuel pump and make it start and continue to run ?
Have you checked to see if you are getting spark when it won't start ?
Could be a relay or coil, ignition module, or other component.

How long since a tune-up? Any applicable trouble codes? If you have that spider fuel system, that system is noted for problems. Check the fuel pressure, key on engine off, 60--66 psi. After it starts it will run with less pressure. In the past I have seen service bulletins about the poppet valves sticking, the fix was a cleaning procedure, that was a shop procedure.
Mainly the bulletin talked about hard starts in the morning because of poppet valves sticking, after it starts it will usually run fine the rest of the day, after it sits overnight, you have the same problem the next morning.
There could be other issues?
If it cranks good but won't start, have a helper crank it while you visually check for spark at the spark plugs. If spark everywhere, use a gage and check proper fuel pressure and fuel injector pulse.

It sounds like the starter solenoid is going bad.

replace your fuel relays

most likey a wrist pin bad or cam bearing and last a rod bearing you need a stethascope to locate it ehrn it's knocking. could even be a pully or belt tensioner.

defective starter

i think u need a neww battery and you will fix ur problem

Need to check for fuel pressure and volume. If you turn the key on and you have pressure, then you should be able to start and run. If your fuel pressure gauge has a releif hose on it, then while running, dump fuel into a jug and the engine should stay running. If the vehicle will not start but cranks over, then turn the key off and on a few times. the fuel pump will only stay on for a few seconds and cycle off. Sounds like you are losing your fuel prime from the pump to the engine. Only fix is to replace the fuel pump if you are losing your prime.

check ignition module in the distributor