It sounds like yours is a very new separation; I was in your position about 9 months ago in terms of trying to arrange a regular schedule (I still don't have a proper one!).
What I've always done is take the view that our DC deserve to have a good relationship with both their mother and father separately, despite the fact that their parents relationships didn't work. They love spending time with both of us.
When we first split, I planned my DC activities as if their Dad was completely out of the picture, as I didn't know his schedule. I had asked that my EXDP let me know when he was able to have our DC. Initially, he would email or text a couple of days beforehand, telling me he was going to pick up our DC that weekend, however I refused visits on occasions that it didn't suit us as we already had plans. After a few goes, he got the message, and will now let me know at the start of the month when he can have them that month. If they haven't already got plans, they go, if they have got plans, then they don't go.
My EXDP still has every chance to make a regular schedule, I constantly ask him to, so that he can avoid missing weeks with our DC, he just chooses to do the last minute thing as he cannot commit to anything (another reason I left him).
The first few times my DC went were hard, really hard for me as apart from the odd night at my parents, our DC, now 5 and 4, had never been away from me. My youngest has additional needs, and has issues sleeping so I was worried about our DC.
The thing that helped is that I generally will FaceTime them when they are with their dad, each night before bedtime. We chat about their day, normal things. I never ask if they are missing me, or if they want to come home. Sometimes my DC will ask what I'm doing, and I will say I'm watching a film or whatever, or just say I'm relaxing.
What can make it difficult is that you go from parenting 100% to 0%, and that can be emotionally difficult, particularly if you are a SAHM. I work full-time as well, so that couple of days to decompress is vital, even if it only happens every 2 or 3 or 4 weeks. Some weekends my DC are away, my calendar is jam-packed, other weekends there's nothing in the diary. I would perhaps find some regular hobbies/classes to do. Also, it really does get easier over time.