Just like everyone else has said, with a low level character, delaying upgrading to VIP for a week or two should not matter,
After you've upgraded to VIP, the characters you already have should be good to go -- there will not be any downside to continue to play those characters that you originally created under your F2P account.
And, above all, welcome to LOTRO! Having played the game for 1000s of hours (literally) myself, I think you have an extremely fun and immersive journey ahead of you.
[COLOR=Lime][SIZE=1]other favorite middle-earth related games: The One Ring RPG, published by Cubicle 7; LotR: The Card Game, published by FFG[/SIZE][/COLOR]