I am planning to go full time at least by summer of 2015 (July or August). I currently have an A cup and can hide them when I am wearing jackets and winter coats. However, when the heat strikes I wonder how am I going to hide my girls except for binding them which I think defeats the main goal of transitioning.
I am lucky that I live in Ontario, Canada - Transgender are given full rights to go full time at work regardless of a legal name/gender change. You just have to let your employer know that this is now my name and you should address me with the correct pronouns. I am not saying that I will not change my name but it's not a pre-requisite.

Ontario Human Rights Commission
13.3.3 Recognizing lived gender identity
Sometimes, a person may choose not to change their name and gender on their identity documents. In other instances, different documents may indicate different names and/or gender designations. Regardless of what is recorded on a person's identity documents, a trans person should be addressed in person by their chosen name and gender.
Organizations should accommodate if a trans person asks them to have documents recognize a name that differs from their legal name.
Example: A trans student requests that class lists reflect their lived gender identity and chosen name. This would help make sure teachers and other staff and students address them appropriately.
Depending on the circumstances, the Code may allow for limits on the duty to accommodate, especially if a person chooses not to change their legal name. An organization would have to show their criteria for recognizing a person's gender identity is legitimate and they were unable to accommodate short of undue hardship (see sections 9 and 10 of this policy on reasonable bona fide requirements and the duty to accommodate). A person's chosen name and gender might still be used alongside their legal name, again, if appropriate in the circumstances.
Example: A trans client requests that electronic health records at their local walk-in clinic reflect their lived gender identity and chosen name alongside current health card information that shows a different name and gender. This would help make sure healthcare professionals and other staff address them appropriately in person.
For prescriptions and other documents, ordering medical procedures and referrals to other health care practitioners, the clinic believes the name and gender shown on the person's health card is also necessary to avoid any health and safety risk from mistakes that might happen.
In many cases, organizations will not need corroboration or proof of a person's lived gender identity to recognize a person's chosen name and gender in their administrative system. A person's request should usually be enough.
Example: The University of Toronto has a policy that allows students to change their name and gender on academic records, class lists and online student databases by writing a letter to their college registrar, requesting this change. The university will require the student to establish and authenticate their identity.[115]
A person's self-identified gender should be accepted genuinely in good faith even if identity documents do not match their lived gender. An organization would need a serious reason to doubt someone's self-identified gender.[116]