Final answer:
Sharif must enter his client's order for Tim Hortons' shares before his own to adhere to professional and ethical standards.
Step-by-step explanation:
Sharif, as an experienced investment advisor, must adhere to ethical and professional standards which dictate that the interests of his clients come before his own. The action Sharif should take when entering these orders is: 1) He must enter his client's order for the shares before he enters his own order. This is in keeping with the industry's best practices and the legal obligations that prioritize client interests above those of the advisor's personal gains. Not entering his client's order first could potentially be a violation of securities regulations and professional codes of conduct, which uphold principles such as fairness, integrity, and putting the client's interests first.