i've already modified my schedule as much as i could. since i have other activities besides practising, i'm not always able to practising at suitable time. thats the reason why i have to start at 8am. on the other hand, another neighbours who live downstairs, only want me to stop between 3-5pm, and they're fine with early and late practising. then comes this neighbour who wants to sue me, because she doesn't mind playing between 3-5pm, but doesn't want playing in the morning or evening. which makes situation rather difficult to please everyone unfortunaltely
Personally I would just do the following.
If there are some legal conditions, play legally. i.e measure the levels yourself, get the appropriate sound proofing, if needed, and then play within any times specified as you desire. That's it, that's all you have to do. Do it once and you'll never have to worry about it again whoever moves in / out or whatever their preferences are.
[You could measure her sound levels too at the same time if you think the noise she makes at 1am is unreasonable]
Beyond that, If you want to take into account some neighbours' preferences, fair enough. But I wouldn't bother, because it'd be like asking them all to come and pick your wallpaper.
If you do, just make it clear to anyone if you say you won't play between 3-5 pm or on Wednesdays or whatever, that you are playing legally, so you don't have to, and that you can't guarantee that you will always be able to accommodate them. Or say nothing and do it if you want [don't give them the opportunity to claim you have some agreement over and above whatever legal requirements there are that you've broken]
The problem with accommodating neighbours ad hoc desires leads to things like this.
To me, 3-5pm is reasonable but 8am less so, but that's just my opinion, which is the problem. It seems that you've been practising with a schedule that worked with old and existing neighbours and are considering the new neighbour to be unreasonable simply because she has her own preferences.