Six months is a little aggressive, usually people take 3-6 months to be productive in a new role. However, it may vary from job to job and person to person.
You will not be perceived poorly if you are a high performer. However, if you are struggling in your current role, or do not get along well with your boss or approving authorities or have a negative image due to any reason( behavior issues, people issues, disciple issues, not meeting commitments etc ) , then it might be taken as negatively.
You have to be very clear on why you want the new job, and why you are a good for for the new job. And then be able to convince others in the management.
The first criteria to take a new job is to be really good at your current job. If you are able to do justice to your current role, only then you will be considered for the next role.
Second thing to I like to follow is to do more, finish your work and then take up more work, preferably from your boss plate( if the new job involves a promotion). I don't mean spend more hours in office. Usually I like to build a high performance team, whom I delegate work, keep track of it, and offload more work from my bosses plate or contribute more to the organization. You may have your own way of doing things.
Lastly, one has to be flexible. Usually, the role comes first and the designation (and the perks) later. If you demonstrate the capability to play the role without the designation ( by picking more work that your current role demands or doing work which the next role demands), people will be willing to give you the opportunity to do it formally.
Typically, no one minds a employee applying for another role. You may not make the cut after six months, but people will take notice, look at your performance and evaluate you. If they feel you are a good bet, then it will be taken as positive. You may not make the cut as someone more experienced or better suited for the role is selected, but you will get noticed and this will increase your chances of getting through in the future.
Of course, all this is assuming that you have a good boss, who is not insecure, in which case, all calculations can be tossed aside :). Just do your job and hope to get a new boss or look for a job change. Never mention manager change as a reason for looking for a new job internally.