Complicating the answer to your question, in the early years there was the small matter of the civil war to fight. Thus control, enforcement etc. was in the context of an armed stuggle already, and the management of the economy similarly was 'facilitated' by wartime conditions eg. hard to have free markets when basic services have collapsed.

After the civil war the answer is still not straight forward as War Communism was supplanted by the New Economic Policy (NEP) which allowed a fair bit of small scale free market activity, reducing the need to enforce.

As to whether there were some areas where people hadnt heard of the Soviet takeover, I've heard stories of this but I don't know how credible they are.

W. Bruce Lincoln's Red Victory covers the economic realities of the civil war (eg. people working in factories in exchange for goods). Alec Nove's Economic History of the USSR also has sections on pre-revolution economic policy, War Communism and later NEP.

It does not really make sense to speak of the "enforcement of communism" in the Soviet Union, as the Soviet leadership (i.e., the Communist Party) did not perceive itself to be enforcing communism but rather creating a socialist platform on which communism could rise.

But OK, that's semantics. As another user has pointed out, initially after the Bolsheviks (or the Communist Party) took power, Russia fell into a civil war that lasted from 1917 until 1922. During this period, so-called "War Communism" dominated political evolution, which, for the average person, meant about what you would expect for a nation embroiled in war for nearly a decade (keep in mind that the revolutions of 1917 occurred near the end of WWI): forced conscription, military occupation of many towns, and requisition of grain from the countryside. It was not until after the civil war and other peripheral wars ended, however, that the Soviet Union came into existence (prior to that, there had been "Soviet Russia," etc.), so your question, which probably wasn't directed at the post-revolution wars anyway, is best directed at the NEP period, which, again, /u/Smilin_Dave has already noted.

Taking a step back from the revolutionary zeal that had dominated Bolshevik politics during the war, Lenin recognized that his new Soviet Union would need to rebuild from years of war if it were to succeed as the vanguard of socialism. He therefore implemented the "New Economic Policy," which allowed for small business ownership and profits. Under this model, the state still controlled the structural elements of the economy, such as steel production, factories, natural resource extraction, and communication networks. There, therefore, no corporate giants like you would expect to see in a free market system. Under the NEP, there was another crucial element: the peasants, some of whom had supported the Bolsheviks during the revolutionary period because they promised to give land to the peasants, were allowed to grow food on their own land for profit. This created a new system of free trade that had not existed prior to 1917 in which the peasants grew grain and sold it to the cities and used their profits to buy goods and services from the cities. Under this new system, many peasants increased their living standards, which was significant in a nation which was not as economically developed as most of Europe and so had a majority peasant population. While all of this went on, the Communist Party was happy to focus its power on building socialism in the cities, where governments could exert power more readily as you suggest (there were, however, no "Five Year Plans" as of yet).

In 1928, with Stalin now in power (that's another story, although he did initially use his supported of the NEP to bypass certain political opponents), the Soviet Union entered a recession. The peasants sold less grain to the cities, which in turn made planning for the cities more difficult. The Soviet government began again requisitioning grain from the countryside, and Stalin made the decision to collectivize the countryside in order to gain control of its grain production. Violence returned to the countryside as peasants were forced to move together into single communities that were to grow grain on large-scale farms. This spawned resistance, but the worst fate was that of the peasants who had became well off under the NEP (the so-called "kulaks") who Stalin labeled enemies of socialism and sent to work camps. At the same time, the Soviet Union implemented its first five-year plan in the cities, thus creating the Soviet bureaucratic control system that we associate with the Soviet Union today.