Despite St Paul, people have abstained in marriage for long periods of time as long as people have been getting married. Reliable NFP has not been around for long, and it isn’t 100%, and there have always been people for whom having a pregnancy would be a very bad thing. So they abstained. Some people have actually stopped having marital relations permanently after finishing having children, instead devoting themselves to other things. Other people are apart for other reasons - my husband is away for half the year in his job, for example, so abstinence is pretty much enforced.
I have no idea what would be an appropriate amount of time for you. I would suggest is perhaps beginning a program of regular prayer, like the daily offices, and doing them together. And make sure to review regularly how abstinence is working in your relationship.
One place you might look for resources is in writings of the Orthodox Church. They fast about 180 days a year, and that includes sex. So they tend to have good information available on such things (good vegetarian recipes too.)