I compose original videogame music and whenever I write a lead guitar track I get either my friend or my dad to play it.
I play acoustic guitar and piano but I have recently started learning how to play lead.
I really want to be able to record my own lead tracks.
I practice about 1-3 hours a day and I always have my guitar with me when I am watching tv or something to practice scales and techniques.
I know no one will know exactly how long it will take but what would be a good estimate based on the information provided?

I would also need it to sound professional, my dad plays guitar so I have all the equipment but I just need to skill now.
It is impossible to say, cause there are too many factors that goes into it. We don't know what you practice, how you practice, the quality of your practice, what level of playing is satisfying to you before you start practicing something new, how much of your practice is focused vs mindless practice etc etc. It is impossible to tell.

The only advice i have is have patience and put the time in. If you are stressed about wanting to play lead parts well the best thing to do is forget about it, stress does not work well in guitar practice. It takes as long as it takes to develop, the focus should be on the journey rather then the destination.
Fusion and jazz musician, a fan of most music.

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Try recording it, either writing out a solo or improvising it to the song you've written. Find out any mistakes/what you need to work on and work on it (ie is it technical or musical?). Practice getting better at any weakness in your playing and constantly record it. If you don't know what needs to be improved, find a local guitar teacher or see if your dad will give you advice. But the main thing is is to constantly record yourself, not hours each day but a little bit. That's a good way you can hear how you sound and pick out any mistakes and constantly improve.

Ok, first of all, you can play guitar while you watch TV, but you will not make much progress practising like this. You need to focus on the guitar alone when you practise. Otherwise, you would be just jamming, as you are not really paying attention to your playing.

What you really need to record lead parts, assuming the parts are all written and arranged, is a really solid rhythm sense. So, rather than focusing on recording the parts to get them down on as demo, record yourself playing them as practice (I would recommend you to do so both on audio and video), and listen; that way you will know what are your faults when playing leads and it will be easier for you to correct them.
I think you should divide your practice time - you say that you practice for about 1-3 hours a day.

Maybe it would be a good idea if you for example have two hours to practice for a particular day - that you practice technique for an hour, and another hour to practice the recording itself. So when you create some kind of music which needs lead guitar part - you record yourself each day over that part. So, even if you feel like you are not yet good enough to record good lead parts it is a great idea to record it anyway. As the days and weeks go by, and you listen to your older recordings - you will realise that your new ones are much better, and that feeling of improvement will make you even more motivated to practice more.

Now, it is hard to say exactly how much will it take you to get to the level you want, but it will sure be a lot faster if you record yourself often, then analyze and correct mistakes.

Btw. - you say that your dad plays lead guitar parts for you - well that means he can help you a lot with this too!