Can I enter form Canada using B visa as my H4 stamping is delayed in Canada? Can i reenter on H4 next time and from that point always use H4?

It seems as if the plan depends upon whether CBP believes that your entry under a B visa is for a short period of stay, and not a substitute to stay in the US for a long period of time in lieu of an H-4 visa. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.