Your thesis should be submitted (both paper copies for examiners and the electronic copy for Turnitin check) after you complete the minimum period of study and before the end of the maximum period of study for your qualification.
For full details on minimum and maximum periods of study, please see University Regulation 6.2.3 (PDF - 129KB). If you are handing in the signed form, you should do so at the Aston Webb Student Hub.
Ultimately, the decision to submit must be yours. You should discuss this with your supervisor, but please remember that their advice and/or opinion are advisory only. This advice should not be taken as an indication that the final thesis will necessarily fulfil the requirements of the degree.
Exceptionally you may be able to submit your thesis early.