Just by the by, it would be nice to have a little more info on background - where you're located (generally, what part of the country/world), how long you've been playing, how long you've been playing this music (we are in Jazz Technique), etc. Because there's things we all do in daily practice no matter where we are, there's things we did when we were first getting into this music, etc.
I do tend to disrecommend the computer generated "play alongs"; personally I've found that having that much information to lean on (rhythm section chugging along playing the changes and form no matter WHAT you play on top of that) coddles a bit too much. If you can communicate your melodic line AND the time AND the harmony (as you hear) with no other accompaniment than a metronome (in individual improvisational practice as per Don), you'll be able to clearly direct the musicians you're playing with in real time. The Aebersold play alongs are a little better in that those are recordings of actual musicians playing actual music accompanying a soloist (who isn't recorded) in real time. But there are a few of those recordings that the time ain't so great (the Bird one comes to mind...).
When you get together with your drummer friend, record yourselves playing and give it a couple of days before you listen to the recording. If you get together twice a week, for example, before you start playing, listen to the previous session's recording with a couple of things in mind:
1. FEELING - does it swing? Does it sound like you're playing TOGETHER or is someone (or everyone) in their own little world ? Is music being made or are you having moments where you both are playing the same tune in the same time stream but you aren't communicating to each other how you each are hearing the tune?
2. TIME - get a metronome out and find your bpm marking for the track and get the click going and listen. CAVEAT: Time breathes. We are human beings and our hearts don't beat precisely in metronomic time, they accelerate when we inhale and slow down when we exhale. So the idea is NOT that you stay precisely ON the click. But if you start out playing at half note=126 bpm, you should end up playing within one or two metronome markings of that time stream ASIDE: I don't have the study in memory and it was done with pitch not time, but it turns out that humans can't hear a difference tuning that is higher or lower than (if I remember correctly) 5 cents. I would have to imagine that it's similar for time stream.
Anyway, if you get OFF the click, just stop the nome and then start it back up ON the beat to see if you've moved around.
As far as other suggestions, if there are tunes that you both are super familiar with, start doing them at different tempos - up tunes as ballads, as waltzes, and vice versa. Then do them at the tempo you usually call them in, but in different keys. See how putting familiar things in an unfamiliar setting affects your time feel.
