I find
https://read.thepositiveword.com helpful, to be able to get the Daily Readings from the same bookmark without having to remember where I'm at in a plan or getting set back by a feeling of having to catch up if I miss a few days.
But I think the most important thing is to remember the point is to build a relationship with your Heavenly Father, not just show up to check in and move on for the day. So discipline, while important and valuable in many ways, isn't always the most productive mindset for this.
Consider from your position of being a father yourself: "discipline" is probably not really the approach you want your daughters to feel about relating with you. While you can certainly still be an effective parent from a position of purely disciplined interaction, it's not likely to be the connecting experience you really desire.
And if they were to come to you, expressing a desire to get to know you better, you probably wouldn't just pull out some family books or photo albums to send them off to read on their own, but you'd sit down with them and go through them together, and tell them the stories and meanings and contexts of things in addition to just viewing the contents of each page.
Or maybe you'd deem that the books aren't the right starting place for now, and choose to do something else with them instead. As a parent, you probably know your children's needs and readiness better than they do, so you probably wouldn't put the responsibility on them to chart out the plan for such an endeavor, any more than you would put them in charge of in determining something like your household's meal plan (unless you really like lots of PB&J and Mac&Cheese). Their role is simply to express the desire for more relationship and then let you lead.
And so I think this is the case with God, too, with us coming to Him from the position of beloved child. It will make Him happy enough that we just say that we want to know Him better and spend more time with Him, but we don't need to overthink logistics or come up with a plan on our own. God wants us to do things with Him, not just for Him, so it's good enough to simply come to Him and just let Him lead.